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
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.
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.
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.
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.
I first saw raindrop cakes at a Japanese restaurant years ago and assumed they were just gone from my life after going keto. Made mine with coconut cream and pressed a few small flowers inside, and pulling them from the silicone molds still felt like a small ceremony.
Fifth time making these. The agar agar took a couple batches to feel comfortable with but it’s pretty predictable now. Last batch I swapped heavy cream for coconut cream and it set noticeably firmer, which works better when I’m leaving them out for a while before serving. Trying the edible flower version next.
Firmer hold is actually why I kept coconut cream as an option in the original recipe. Good call for longer serving windows. The edible flowers are worth it, they look wild through the clear layer.
Never used agar agar before and I’m kind of obsessed with how these look. Starting with the clear version before I get ambitious with colors. If they don’t set after 30 minutes, is that usually a dissolving issue, or can other things throw it off?
Boiling it fully is the other big one. Agar has to hit a real rolling boil to activate, not just simmer. If dissolving looked fine, that’s where I’d look.
I’ve never used agar agar before and I’m not sure what to look for when it’s dissolving in the saucepan. Is it supposed to look completely clear before you add the rest of the water and vanilla, or does it stay a little cloudy? Just want to make sure it sets up correctly.
Starts cloudy, clears up as it heats. I look for no visible granules and a mostly clear liquid before adding the rest. Full boil is what gets it there, not just a simmer.
Used coconut cream instead of heavy whipping cream and it set up perfectly. Wasn’t sure it would work but you honestly can’t tell the difference. Great option if you’re dairy-free.
Raindrop Cake
How do you calculate to 0.2 net carbs? I don’t see any fiber content listed. Are the edible flowers calculated to all fiber?
Thank you
Curious
