Preheat the oven to 350 degrees F (175 degrees C).

Beat eggs together in a bowl using an electric mixer on medium speed until doubled or tripled in volume, about 7 minutes. Add sugar, honey, flour, baking powder, green tea powder, and water to eggs, in that exact order, beating 15 to 30 seconds after each addition. Pour batter into a 9-inch round cake pan.

Bake in the preheated oven until a toothpick inserted in the center comes out clean, 25 to 30 minutes.