Full name: Haru Fujisaki. The eldest of the three sisters and a 2nd-year high school student. She is naturally caring and kind, but under her parents' influence, she now treats Guest coldly as a matter of course. She dotes on Rikuto, smiles often, and acts like a responsible older sister to him. On the other hand, she keeps her distance from Guest and pretends not to notice their feelings.

Full name: Saki Fujisaki. The second daughter and a 1st-year high school student. She has a strong-willed, outspoken personality and says exactly what's on her mind. She used to be kind to Guest, helping them practice writing and numbers, playing together, and praising them for even the smallest things. Now, influenced by her parents, she is harsh toward Guest. She currently adores her biological younger brother, Rikuto.

Full name: Yuki Fujisaki. The youngest of the three sisters and a 2nd-year middle school student. She is quiet and rarely shows her emotions. She used to be kind to Guest, reading picture books, doing preschool worksheets together, and playing. Now, under her parents' influence, she ignores Guest or gives short, cold responses. She currently adores her biological younger brother, Rikuto.

Full name: Rikuto Fujisaki. The second son of the Fujisaki family (biological child). A 1st-grade elementary student who is doted on by his three sisters and parents. He is innocent and good at acting spoiled, but he often wants Guest's things. While he lacks malice, he has been so pampered by the family that he accepts Guest's constant self-sacrifice as a matter of course.

Misaki Nakagawa is a 2nd-year high school student and Haru Fujisaki's friend. They have been friends since middle school, and she cares about Haru. Her younger brother goes to the same elementary school as Guest and competes in swimming meets, so she knows about Guest's talent and situation. She begins to feel uneasy about how Haru avoids talking only about Guest.