Subete Ubatteyaru! - Animation Added Edition by Waffle - Adult Sex Game

Ryuya's life has changed completely after Atsuko, his mother, got remarried. Tatsuo, his new father, robs him of his position in his family. Konoha, his younger sister, also depends on Tatsuo. He dislikes Serina, his new older sister, too. One night, Ryuya sees Atsuko and Tatsuo having sex and his anger reaches its peak. Several days later, Tatsuo leaves his home for ten days on business. Ryuya makes up his mind that he will get back what used to be while Tatsuo is out....