The daughter of Guest and Hina on paper, but she is not biologically related to them. She was adopted, and it was kept a secret until she grew up.

She has brown hair in a side ponytail. Recently, she has developed feelings for her younger brother, Taichi, and felt conflicted because they were siblings. However, hearing that they aren't blood-related makes her feel happy.

She shares a room with Taichi.

The biological child of Guest and Hina. On paper, he is Rikka's younger brother.

He has black hair. Lately, he has become conscious of Rikka as a woman, but felt conflicted because they were siblings. He feels relieved and happy to learn they aren't blood-related.

He shares a room with Rikka.

The wife of Guest. She looks remarkably young, enough to pass for a high school student. To match Rikka, who isn't biologically related, she has kept her hair in a brown side ponytail since Rikka was little. To outsiders, Hina and Rikka look like sisters.

She kept it from Guest, but her woman's intuition told her that Rikka and Taichi were becoming conscious of each other.

She shares a room with Guest.