【Matcha Sponge Cake】Put 15g (1.3 Tbsp) granulated sugar in a small bowl. Strain matcha powder and put in the bowl. Mix well.

Add 3 Tbsp hot water and mix well.

Add milk and mix well. Carefully crush small lumps with spatula.

Preheat an oven to 210℃ / 410ºF. Prepare hot water to warm egg mixture. Sift cake flour twice.

Beat egg lightly until it becomes watery. Add granulated sugar and mix lightly. Warm it in the hot water until it reaches body temperature.

Whisk it with a hand mixer on high speed. Whisk until the trace of the dropped batter remains for a moment. Whisk it for a minute on low speed.

Add matcha mixture while mixing on low speed. After all mixed, whisk it for a minute on low speed. Mix the batter of the end to make it evenly.

Add the flour in 3 parts while sifting it again. Fold it. After all added, continue to mix for 3 min.

Mix it until the trace of the dropped batter gets blurred soon. Pour it into a baking tray. Flatten it. Drop the tray to remove big bubbles.

Bake it at 180℃ / 356 ºF for 18 min. Drop the tray to prevent shrinkage. Let it cool.

【 ''KOSHI-AN'' paste】Mix well sweet azuki bean paste and warmed milk.

【Cream】Put heavy cream in a bowl. Add granulated sugar. Whip it with a hand mixer on low speed while cooling with ice water. Whip it until it starts to thicken.

Put it out from the ice water. Add vanilla essence. Whip it with a whisk until soft peaks form. A whisk can make the cream smoother than a mixer.

【Spread the cream and roll.】Peel off the lining paper from the sponge. Spread a plastic wrap over it and turn it upside down. Put the azuki bean paste on it and spread.

Put the whipped cream on it and spread. Thin the cream of the edge. Roll it tightly at first. Lift the plastic wrap and push and roll.

Wrap it with parchment paper and then wrap it with plastic wrap. Let it sit in a fridge for overnight to make the sponge moist. It's all done!