Niimi Yuzuki

"A Step Sister Who Can't Get Used to Being a Younger Sister (妹になりきれない義妹)"

The little step sister of the protagonist, the two are having a hard time grasping the distance in their relationship. She's a very reserved girl.
The protagonist's father and her mother have remarried, and they have come to live together a year before the story starts.

The two still haven't completely opened their hearts to each other and she has yet to call him "onii-chan". However, as the two spend their time together, she gradually opens herself to him and grows attached to him, acting spoiled like a puppy.

Although she's meek, the core of her personality is strong and she's the type to work hard towards a goal.
Yuzuki loves sweets.