Daikichi Kawachi
Voiced by: Hiroshi Tsuchida
Portrayed by: Kenichi Matsuyama
A 30-year-old bachelor. At his grandfather's funeral, he meets Rin and decides to take care of her. Inexperienced with kids, he has a lot to learn so he can care for Rin properly.
- Gracefully Demoted: Daikichi willingly takes a demotion to regular staff in order to forfeit mandatory overtime, and have more personal time to properly father Rin.
- Identical Grandson: He looks almost near identical to his grandfather in his youth. Their resemblance helps Rin latch onto him.
- Is That Cute Kid Yours?: Daikichi frequently gets mistaken for Rin's father. He usually doesn't mention that he is her nephew.
- Ma'am Shock: Daikichi, who is only 30, has a negative reaction to being called "oji-san".
- Manchild: Downplayed. He's not too childish, but being a 30-year old bachelor, he is completely unprepared for parenthood.
- Will They or Won't They?: He has this with Yukari, Kouki's mother. The adaptations end on an ambiguous but optimistic note, while the manga ends on a "won't".
Rin Kaga
Voiced by: Ayu Matsuura
Portrayed by: Mana Ashida
The six-year-old illegitimate daughter of Daikichi's grandfather, making her his aunt. She is taken in by Daikichi after his grandfather dies.
- Adaptational Dye-Job: Her blonde hair is darkened to black in the live-action film.
- Adorably Precocious Child: Rin's a bit precocious for her age, being somewhat more mature than most six year olds and knowing how to cook a bit already.
- All Girls Want Bad Boys: Averted. She is driven away from Kouki after he goes through a "bad boy" phase.
- Calling Parents by Their Name: She calls Daikchi by his name because she doesn't consider him her father and because her biological father is deceased.
- Childhood Friends: She meets Kouki in day care and they stay close into their teens.
- Childhood Friend Romance: As a teen, she develops feelings for Kouki. It doesn't work out between them.
- Death Is a Sad Thing: Being six, she doesn't have that much of a grasp on death. Her father dying causes her to have an existential crisis due to anxiety that she or Daikichi will die soon.
- Elective Mute: Rin initially doesn't like to talk around strangers.
- Embarrassing Damp Sheets: Early in the series, she begins wetting her bed due to stress. Rin insists that it's just sweat.
- Happily Adopted: Zigzagged. Rin loves Daikichi, but it's made explicit that she doesn't consider him her parent figure. In the manga this is foreshadowing to her eventual attraction towards him.
- Mukokuseki: Her blonde hair and its unusual hair texture implies that her biological father might be at least partially white.
- Parental Abandonment: Her mother isn't in her life and her father died. Her biological father is actually just absentee.
- Parental Title Characterization: She calls her father "Grandpa" not to be demeaning, but because he was a senior.
- Promoted to Love Interest: Inverted. Both the animated and live action adaptations ignore any foreshadowing towards Rin being Daikichi's eventual wife and cut off before the Genre Shift Time Skip.
Masako Yoshii
Voiced by: Maaya Sakamoto
Portrayed by: Mayu Kitaki
Rin's biological mother who works as a mangaka for a living.
- Parental Abandonment: She is Rin's rather young mother who left Rin with her father, or really just a man she worked for. Even after Daikichi finds her, she doesn't want anything to do with Rin.
- Workaholic: She devotes all her time to her career and refuses to give it up to raise a kid.
Kouki Nitani
Voiced by: Noa Sakai
Portrayed by: Ruiki Sato
A boy Rin befriends in her daycare. He's a bit of a brat, but has grown fond of Rin as they are both raised by a single parent.
- Disappeared Dad: His parents are divorced. In the film adaptation, his father is dead. His mother lied about the divorce to lessen the trauma on her son, though he already guessed it.
- Childhood Friends: He meets Rin in day care and they stay close into their teens.
- Childhood Friend Romance: As a teen, he develops feelings for Rin It doesn't work out between them.
Yukari Nitani
Voiced by: Sayaka Ohara
Portrayed by: Karina Nose
Kouki's mom. Like Daikichi, she's raising her child by herself and gives him advice on occasion.
- Will They or Won't They?: From the get-go, she has a lot of Ship Tease and Unresolved Sexual Tension with Daikichi. The anime ends on an ambiguous but hopeful note but the manga has them not ending up together due to not wanting to cause problems with Rin and Kouki's relationship.
