Light and faintly sweet, this keto raindrop cake wobbles on the plate and practically dissolves on your tongue, my agar take on Japanese mizu shingen mochi at 0.2g net carbs. I let the agar and sweetener dissolve at a boil, pour the mixture into half moon molds, and I refrigerate about 30 minutes until set. Cream and food coloring turn some of them pastel.
I first saw these at a Japanese restaurant years ago and spent a while figuring out how to make them at home without sugar. The original Mizu Shingen Mochi uses mineral water and agar to create a wobbly, crystal-clear dome that looks like an actual drop of water on a plate. My version swaps the sugar for a powdered sugar-free sweetener, keeping everything low carb and keto-friendly without losing that stunning, show-stopping look.
What I love about this recipe is how much room there is to play. The base is clear with just a hint of vanilla, but from there you can go in a dozen directions. I've done cream-based versions with heavy whipping cream or coconut cream that set up opaque and take food coloring beautifully. I've pressed edible flowers into the clear version for something that genuinely looks like art. And I've been experimenting with matcha powder and cherry extract for Japanese-inspired flavor variations that are nearly impossible to find in other sugar-free dessert recipes.
The texture sits somewhere between a jello whip and a keto chocolate mousse, but more delicate. It wobbles on the plate, holds its shape just long enough to impress, and practically melts on your tongue. If you've made my stained glass cake, you already know how agar behaves.
One thing I should have mentioned sooner: these are best served within 20-30 minutes of coming out of the fridge. They hold up fine while chilled, but at room temperature the gel starts softening and loses its dome shape. I learned this when I left a batch on the counter during a dinner party. They'll store in the refrigerator for up to 5 days (I keep them in the molds until serving), but plan to unmold right before you're ready to eat.
The macros above are calculated for the clear, non-cream based version. They are for one cake. If you choose to include cream in two-thirds of your batch, your macros for each cream version:
Calories: 80 Fat: 8g Total Carbs: 6.8g Net Carbs: 0.8g Protein: 0.2g
How I make water drop cake
My version skips the traditional soybean powder and sugar syrup. Here’s how I make it.
Boil water, agar agar powder, and sugar-free sweetener together.
Stir in vanilla extract and the remaining water.
Divide the mixture into 2-3 bowls if you want colored or cream-based versions. Keep one bowl clear. Add 1/4 cup heavy cream or coconut cream and food coloring to the others.
Pour into silicone molds. For edible flowers, fill molds halfway, press in the flower, then top off with the remaining mixture. This suspends them in the center instead of letting them sink to the bottom.
Refrigerate for 30 minutes or until set.
Getting a crystal clear result
I’ll be honest: my versions aren’t always perfectly crystal clear. This recipe is meant to be a quick, fun adaptation, not a technique showcase. But if clarity matters to you, here’s what I’ve learned after testing this more times than I can count.
Check which agar you’re using. This is the one I wish someone had told me first. Japanese-style agar (sometimes labeled kanten) sets noticeably clearer than the standard agar powder at most US grocery stores, which leans hazy even when you do everything else right. If your gel keeps clouding after nailing every step below, the powder itself is usually the reason.
Use quality water. The original Japanese version uses water from the Southern Alps of Japan. Tap water sometimes has sediment that makes the gel slightly hazy. Filtered or mineral water helps.
Dissolve agar powder fully. I add it slowly to the pot while stirring constantly. It starts cloudy and clears up as it heats. I look for no visible granules and a mostly clear liquid before adding the rest of the water. If you get clumps, strain through a fine mesh sieve.
Hit a real rolling boil. This is the step that catches most people. Agar has to reach a full boil to activate, not just a simmer. If yours didn’t set, this is almost always why.
Measure the agar precisely. More agar is not more insurance. Going over the amount makes the gel stiffer and cloudier at the same time, which is the most common failure I hear about from readers. You want just enough to hold the dome shape, so it stays delicate and wobbly instead of bouncy.
What is agar agar powder (and why I use it)
Agar agar (or agar powder) is a plant-based gelling agent used in Asian cuisines and in desserts like jellies, puddings, and custards. If you’ve made my keto gummy worms, you’ve worked with a similar concept, though those use gelatin instead.
I prefer agar for this recipe because it’s odorless, tasteless, and gives a cleaner, more translucent result than gelatin at the same concentration. It’s also naturally vegan. The catch is you have to boil it fully (a simmer won’t cut it), and it sets at room temperature rather than requiring refrigeration. That’s actually why these cakes can soften if you leave them out too long.
Traditional toppings (and what I use instead)
Traditional Mizu Shingen Mochi comes with two specific accompaniments:
Kuromitsu (black sugar syrup): A thick, dark brown syrup made from caramelizing black sugar and water. Obviously not sugar-free. For a swap, I make a simple syrup with allulose and about half a teaspoon of blackstrap molasses for color. Not identical, but it gets you in the neighborhood.
Kinako (soybean powder): A flour made from roasted soybeans. Kinako is actually naturally low in carbs, so you can dust this on without worry. It has a nutty flavor similar to peanut butter.
I store these in the refrigerator for up to 5 days. I keep them in the molds until I’m ready to serve, which protects the shape and prevents them from picking up fridge odors (a tip from reader Keisha that I now follow every time).
Plan to serve within 20-30 minutes of unmolding. At room temperature, the agar gel softens and the dome starts to flatten. This is not a dessert you can plate an hour before guests arrive. I set them out right as we sit down. Reader Drew found that using coconut cream instead of heavy cream gives a noticeably firmer set, which helps if you need a little more counter time. For a dairy-free dessert that holds up longer at the table, try my dairy-free ice cream.
These do not freeze well. The gel structure breaks down and they won’t hold their shape after thawing.
What is a raindrop cake
This is a clear, jelly-like cake traditionally made from mineral water and agar, a gelling agent from seaweed. In Japan, it's a traditional confection called Mizu Shingen Mochi, created by Kinseiken confectionery in Yamanashi to showcase the region's mineral water from Mount Kaikoma. You can see right through it, like a water droplet on a plate. Traditionally served with black sugar syrup and roasted soybean powder.
My keto version is far from traditional, and I did that on purpose. I use tap water instead of mineral water (although mineral water works too). I skip the kuromitsu and soybean powder entirely. Instead I add cream, vanilla, and food coloring for a fun, customizable version that's closer to a keto cheesecake fluff in spirit than a purist Japanese dessert. Think of it as a keto mochi made almost entirely of water.
What does it taste like?
The flavor is mild. I add vanilla extract to mine, but you can swap in any flavoring you like (lemon, cherry, almond all work). Traditional versions are also mildly flavored since most of the taste comes from the syrup and powder served alongside. Without those, the texture is really the star here.
In a medium saucepan, heat 1 1/3 cup water, agar agar powder and sugar free sweetener over medium high heat until boiling. Remove from heat.
For this step
1 1/3 cup water
2 1/2 teaspoons agar agar powder
1/2 cup powdered sweetener
2
Flavor
Stir in vanilla extract and 1 1/3 cup water.
For this step
1 teaspoon vanilla extract
1 1/3 cup water
3
Divide, color, and add cream
Divide mixture into three bowls. Keep one mixture clear. To the other two bowls, add 1/4 cup heavy cream and food coloring to each bowl. Mix until combined.
For this step
1/2 cup heavy whipping cream (two bowls get 1/4 cup each)
food coloring
4
Pour into molds
Pour mixtures into silicone molds and add edible flowers if using.
5
Refrigerate to set
Refrigerate molds for about 30 minutes or until set. Remove from the molds. Top with whipped cream if desired.
Nutrition
Per serving: 1 cream cake
Calories
48
Fat
4.8g
Protein
0.2g
Total carbs
6.6g
Fiber
6.4g
Net carbs
0.2g
Nutrition is an estimate calculated from the ingredients listed. Brands vary, so check labels if you track closely.
Frequently Asked Questions
Why did mine turn out cloudy instead of clear?
I've had cloudy batches too, and it's almost always one of two things. Either the agar powder didn't fully dissolve (I look for no visible granules and a mostly clear liquid before adding the remaining water), or the water itself had too much sediment. Tap water works fine most of the time, but if clarity is your goal, try filtered or mineral water. The other thing I always check is whether I actually hit a rolling boil, not just a simmer. Agar needs that full boil to activate properly.
How long can I leave these out before they start melting?
I give them about 20-30 minutes at room temperature before the dome starts to soften. They won't completely collapse right away, but the shape gets noticeably less crisp after that window. I unmold mine right before serving and keep the rest in the fridge until needed. If I'm making them for a party, I bring out a few at a time rather than plating everything up front.
Can I use gelatin instead of agar powder?
I've tried it, and it works with tradeoffs. Gelatin gives a slightly different texture (less delicate, more bouncy) and the gel comes out murky instead of crystal clear. If transparency isn't important to you and you prefer gelatin's texture, go for it. Use similar ratios. But for that classic see-through look, I always reach for agar.
How do I know when the agar is fully dissolved?
I watch the pot closely during this step. It starts cloudy when you first add the powder, then gradually clears up as it heats. I'm looking for no visible granules floating around and a mostly clear liquid. The key step most people miss is bringing it to a full rolling boil, not just a simmer. That's what activates the agar and gives you a proper set. If yours didn't firm up after 30 minutes in the fridge, this is almost certainly the issue.
What is a keto-friendly substitute for kuromitsu (black sugar syrup)?
I make a simple syrup with allulose and water, then stir in about half a teaspoon of blackstrap molasses for that dark color and slight bitterness. It's not a perfect replica of kuromitsu, but it gets the flavor profile close enough. If you want something richer, try melting my keto caramel candy into a thin drizzle. You could also just serve with whipped cream or sugar-free chocolate syrup if you want to skip the traditional angle entirely.
What edible flowers work best inside the clear version?
I buy mine from a food-safe source online (Etsy has several good shops) rather than picking from my garden, since not all flowers are safe to eat. My favorites for pressing inside are pansies, violas, and small roses because they lay flat and look incredible through the clear gel. Other edible options include citrus blossoms, daisies, dandelions, hibiscus, lavender, lilac, and sunflowers. I've found that smaller, flatter flowers work best since bulky ones can distort the dome shape when the gel sets around them.
Can I make this recipe vegan or dairy-free?
I've done both and the results are just as good. Agar powder comes from algae, so it's already vegan. For the cream-based version, I swap heavy cream for coconut cream and it sets up beautifully (actually slightly firmer, which my reader Drew confirmed after his 5th batch). Full coconut milk works too if you want a lighter, less opaque result.
Can I use different mold shapes and sizes?
I've used everything from the half-moon silicone molds in this recipe to small spherical molds and even muffin tins. Any shape works as long as it's silicone so you can flex the mold and pop them out without cracking. The molds I recommend are my preferred size because each one gives a nice portion-controlled serving, but there's no reason you can't go bigger or try different shapes.
How close does this get to actual mizu shingen mochi? Genuinely close, which I wasn’t ready for. Most agar versions overcorrect on sweetener and that lightness the original has is just gone. This one keeps the restraint, you actually taste the vanilla rather than just the sweetness. One thing though: the cream layer is doing real work here, I’d call it required rather than optional.
Tried these last weekend and got totally hooked on how they look, but ran into trouble at the dividing step. By the time I split the mixture into three bowls and stirred in the colors, the clear portion was already seizing up. I was moving as fast as I could. Agar gels so much faster than I expected. Do you keep the saucepan on low heat while you’re doing the coloring step, or is there a short window after pulling it off where it stays pourable? I really want that cream layer inside the clear one like your photos show, but everything went gloopy before I could get there. Trying again this weekend, hoping to nail the timing.
Rebecca, keep the saucepan on its lowest setting the whole time you’re dividing. That’s the key and it should be in the recipe. I also keep a heat-safe measuring cup by the burner for whatever portion I’m holding while I work the other bowls. For the cream inside the clear one, pour it into the mold first, wait about 30 seconds until the surface just barely starts to firm, then pour the warm clear mixture around it while they’re both still liquid. That’s your window.
I assumed agar would give the same rubbery chew as gelatin and almost passed on this. Doesn’t work that way at all. The set is softer and the dome releases from the half moon mold cleaner. Also dissolves faster than any gelatin mold I’ve tried.
I tested the gelatin version early on and the murky set was an instant no. The dome release and dissolve speed being different was honestly a bonus I didn’t expect.
Something about the way this just vanishes the second it hits your tongue is so freaking addictive, I’ve made it probably six times now and I still can’t explain it to people (they look at me like I’m describing a science experiment). Started pressing chamomile flowers into the cream layer on batch four and the whole thing just feels more put-together now, like something you’d pay twelve dollars for at a fancy cafe. These have basically replaced every other summer dessert in my house, nothing else even makes sense when it’s this hot.
Made a double batch on Sunday with the half moon molds and lined them up in the fridge for the week. Figured they’d get watery or collapse by day three, but pulled them out Thursday and still had that same clean wobble. Ten-minute prep, easy to keep a batch going. Gonna have a tray in there every week now.
My daughter poked it like five times asking ‘what even IS this’ before she ate two in a row, so that’s basically the review (mine’s a four only because I still can’t get the cream layer to sit where I want it).
Two in a row after five pokes, I’ll take it. For the cream layer, try letting the first clear pour cool for 3-4 minutes until the surface is just barely tacky before you add the cream. Too early and it sinks, too late and you get a hard seam between layers.
This is probably my fourth or fifth time making these and I finally feel like I’ve got it down. The first couple of batches I used heavy cream and they were good, but I switched to coconut cream and the flavor got this subtle sweetness that really works with the vanilla. I also started refrigerating them an extra 15 minutes past the 30 the recipe calls for, and they come out of the mold so cleanly now (first time I tried to remove them too early and one just collapsed, lesson learned). I’ve been pressing in little purple edible flowers from the craft store and they look so pretty that people don’t believe I made them myself. Not quite 5 stars just because agar agar took me a couple tries to get comfortable with, but once you get the feel for it this is genuinely fun to make and I keep coming back to it.
I saw mizu shingen mochi at a Japanese restaurant four years ago and couldn’t have it because I was already keto, and I grieved that a little. Made these tonight with tiny purple flowers pressed inside the clear layer and the wobble when they came out of the mold is exactly right, exactly what I remembered staring at across the table. I was nervous about the agar agar setting properly but thirty minutes and they were perfect. So, so grateful this exists.
Made these for my daughter’s birthday dessert table and she refused to eat hers for like 20 minutes. Just kept poking it to watch it wobble. When she finally did, she looked up and asked if we could have them every birthday from now on.
Ha, the wobble gets people every time. Agar holds that jiggle longer than gelatin so she probably could’ve poked it for another 20 minutes. Birthday tradition locked in.
Used brewed butterfly pea flower tea instead of about a cup of the water and the color was way more interesting than anything from a bottle. Unmolded on a white plate it goes from deep purple to blue-violet depending on the light. Doing it with coconut cream next batch for a tropical version.
That light-shift on a white plate is so cool. Butterfly pea tea goes pink with anything acidic, so squeeze some lime into the coconut cream batch and try a two-pour, blue layer on bottom, pink on top.
Used coconut cream instead of heavy cream and the flavor was noticeably more delicate, almost floral. Also figured out that letting the agar mixture cool for about 3 minutes before pouring into the molds keeps the edible flowers suspended instead of sinking straight to the bottom. Would be 5 stars if that tip was in the instructions, but worth sharing either way.
Coconut cream brings that floral note, I’ve noticed it too. The 3-minute rest before pouring, I’ve had flowers sink on me more times than I’d like to admit. Adding that to the recipe.
Made a double batch across two silicone molds and they hold up fine for 3 days refrigerated. Cover them while still in the mold before they set (way easier than trying to wrap after). I use a touch more vanilla than called for since the flavor softens overnight.
Oops, yeah, the vanilla fading overnight is something I noticed during testing and just never put in the recipe. Covering in the mold before they set is so much easier than wrestling with plastic wrap after they’ve set.
Brought these to a spring dinner last weekend and nobody could figure out what they were looking at. One person kept poking hers with a fork waiting for it to collapse. When it dissolved the second it touched her tongue, the whole table lost it. Four stars because my first batch came out slightly cloudy (I think I poured while it was still too hot) but the flavor and that texture are unlike anything I’ve made before. Trying the cream layer version next time.
Ha, somebody always has to test it. You already figured out the cloudy thing – wait until the pot barely feels warm before pouring. Cream layer is my favorite of the two.
Round silicone ice cube molds work fine. Agar sets pretty uniformly regardless of depth, so the refrigeration time doesn’t really change. Two hours minimum and you’re good.
Brought these to a dinner party last weekend and the pause when I set the platter down was worth the whole project. Nobody could figure out what they were looking at (one guest kept insisting it was a prop). The wobble when you carry them is half the theater. I pressed edible flowers into each one, and by the end of the night two people had already pulled up silicone mold options on their phones. Making a double batch for Easter with pastel food coloring layered into the cream.
Two people searching for molds mid-dinner is the best review. I do about 10 minutes between each color pour. Any less and they bleed together, much longer and they won’t stick.
Never worked with agar agar before. Honestly pretty nervous about it, kept second-guessing the ratios the whole time it was heating, convinced I’d end up with something rubbery and weird. But it came together, and when I turned them out of the molds after 30 minutes, they actually wobbled. I just stood there poking one for a second. The texture felt unreal, like water that forgot to be water. The vanilla is subtle too, almost weirdly light for a dessert.nnQuick question: I tried pressing a few strawberry pieces in before refrigerating and they sank straight to the bottom. Is that just because agar sets so fast, or is there a trick to getting fruit to stay in the middle?
Yeah, agar sets fast enough that anything you drop in just falls. Pour half into the mold, wait until the top is tacky (10-15 minutes at room temp), press the strawberries in, then pour the rest over. They’ll stay where you put them.
Made a double batch on Sunday and they held up in the fridge for three days without weeping or losing shape. Just cover them loosely before unmolding or they pick up fridge smell. The agar agar is more forgiving than gelatin for batch prep, which I didn’t expect.
Three days is impressive. The agar holds way better under refrigeration than gelatin does (I expected the opposite). Loose cover is smart, fridge smells get in fast.
