Preheat the oven at 350F (175C). Grease inside 9"x5" (bottom 8"x4") loaf pan.

In a medium bowl, mix eggs, yolks, and water. Sift cake flour, Matcha powder, and salt together into another bowl. Set aside.

Put soft butter in a bowl of a stand mixer and beat with paddle for 2 minutes. Slowly add sugar in 4-5 parts, beating for 5 minutes until the color turns very light and it becomes fluffy.

Then slowly add the egg mixture, pouring in 4-5 parts taking another 5 minutes. Fold in the flour mixture in 4-5 parts by hand.

Pour the batter into the prepared pan, flatten the surface with a spatula, and bake in the oven about 1 hour. Cool slightly and remove the cake from the pan. Cool the cake completely on a cooling rack.