

Hi Sébastien (ou bonjour, je parle aussi français ^^)
Those type of wagashi are called mizu-yokan (“water jelly”). They are mostly made with red or white azuki bean jam cooked with sugar and kanten (called agar agar in occident, which is a kind of seaweed). You can then add many things, from kudzu flour to matcha, yuzu juice or food coloring.
For the layers, you first pour the first color, let it sets a moment in the fridge, then simply add the next one etc. The process is not really difficult, just a bit time consuming if you want a clear jelly :)
You’ve got several recipes on the net, this one has many pictures showing the process.
Hope it helps! All the best to you
personal collection
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