Paradise Route

One day, an angel princess named Gatsu Hime was looking down on Earth and ended up falling down. While she fell, two feathers fell from her wings. One from the left and one from the right. The two feathers went into twin brothers, Taihou and Emiya Nagatsuka. Because of the loss of her feathers, she lost her wings.
Gatsu was banished from heaven until she could retrieve both feathers and get her wings back. The problem is, the boys won't give Gatsu the feathers so easily. Also, they don't even know how. Gatsu's only option is to live with the two boys until the day she can finally go home. And so, their life together begins.