かすたむ☆しすたぁ～おれチンのいいなり～

あらすじ

Seiya and Yukine finally start to go out after being friends since childhood. While they were shy about it first and had their doubts, their relationship quickly turned into a passionate one and led them explore their sexuality to the fullest... Which even included Amane, older sister of Yukine later on...

Custom Sister ~Orechin no Iinari~ allows you to customize Yukine's appearance before you start the game.