Combine green tea powder and milk in a bowl and mix well.
Add whipped cream and sugar, then whip with a whisk until smooth.
Place a sponge cake sheet in a container.
Evenly soak the cake sheet with syrup.
Spread the green tea whipped cream evenly over the cake.
Repeat the process 2–3 times to create layers.
Sift green tea powder over the top layer.
Refrigerate for at least 2 hours until set, then enjoy with a spoon.