- 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".
- 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.
- Ambiguously Brown: Her blonde hair and its unusual hair texture implies that her biological father might be at least partially white.
- 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.
- 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.
- Missing Mom: 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 to do with Rin.
- 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.