I Picked Up a Female Dog.

Unable to leave them behind, he decides to take them in. However, since the girls lack knowledge about sex, they do not recognize erotic activities as such. Thus, the protagonist, as their master, cleverly deceives them and begins erotic training. The game involves interacting with them through conversations, outings, and gifts to raise affection and obedience levels, while also engaging in teasing and training to increase their lewdness, eventually leading to various endings including a harem route.