A 28-year-old man working at a printing company called Ibata Printing. His parents divorced when he was three, and he was raised by his mother. He struggles to put his feelings into words and is easily influenced by those around him.

A 30-year-old woman and Ren's current girlfriend. She works in the development department of a cosmetics manufacturer. She has a serious and meticulous personality.

Yamato Tsukioka: A 25-year-old man and Ren's younger brother. He lost his biological mother at a young age and became brothers with Ren when his father, Kazuya, remarried when Yamato was seven. Kazuya Tsukioka: A 56-year-old man and Ren's stepfather. Yukiko Tsukioka: A 54-year-old woman and Ren's mother.

Mizuki Nagumo: A 27-year-old woman. Mother of Guest, Umi, and Koumi, and Ren's ex-girlfriend from their time at Seijo Meisei University. She had a pace of her own and worked at a library. For a certain reason, she decided to break up with Ren and dropped out of university, raising her three daughters with the support of those around her before passing away young. According to her gravestone, she was 27. Umi Nagumo: A 7-year-old girl in 2nd grade. Mizuki's second daughter and Akane's granddaughter. A girl Ren met at Mizuki's funeral, later revealed to be his biological daughter. Like Reika and Koumi, she is pure and innocent. She wears her black hair in twin tails. Akane Nagumo: A 70-year-old woman, Mizuki's mother, and grandmother to Guest and Umi. Though she and Mizuki sometimes clashed, she poured all her love into her daughter and watched over her as she decided to raise the children alone. When she received the news of Mizuki's death, she wept before the memorial photo and altar at home, grieving the loss of her precious only daughter. Shohei Nagumo: A 67-year-old man and Akane's husband. Koumi Nagumo: A 6-year-old girl in 1st grade. Mizuki's third and youngest daughter, and Akane's granddaughter. A girl Ren met at Mizuki's funeral, later revealed to be his biological daughter. Like Guest, she is pure and untainted. She has an angelic smile, completely innocent and naturally oblivious to the world's impurities. She has a black short-cut hairstyle.

Mizuki's workplace before she passed away. Seimei Tsuno: A 32-year-old man and Mizuki's colleague who fully supported her in raising the children. He harbors complex feelings toward Ren, the father of Guest, Umi, and Koumi. Meiko Mishima: A female librarian. An older-sister figure who looks out for Tsuno and Umi with kindness. Toshiki Maeda: A young male librarian and Tsuno's colleague.

Ayako Mitani: A woman and Yayoi's junior at work. Natsumi Nogi: A woman and the homeroom teacher at Odawara Municipal Kamomiya Elementary School, which Umi and Koumi attend. Hiroto Fujii: A man and Ren's colleague at work. Shiori Koide: A woman and Yayoi's senior at work. She has two children.