About Kiss x Sis Manga:
Keita Suminoe has two older (not blood-related) twin step-sisters who love him in a lustful way and have no problems expressing it in Kiss x Sis Manga.
They even like to compete about it; much to the laughter of his friends (which he usually endures without problems). One day they come to his school to give him his lunch, resulting in him getting angry due to the atmosphere.
To counteract his anger, they confess their tender feelings for him in front of everyone and leave. Feeling sorry he chases after them and says that he’ll study hard in order to get in the same high school as them.