|Name in Japanese||九重 凛|
|Voice Actor (English)||Trina Deuhart|
|Relatives|| Roku Kamihara (Biological father)|
Aki Kokonoe (Mother)
Reiji Kokonoe (Cousin, stepfather)
|Title|| Seductive little vixen|
Class 4-1 representative
|Affiliation/s|| Daisuke Aoki (Teacher, fiance)|
Mimi Usa (Friend)
Kuro Kagami (Friend)
Kyoko Hoin (Teacher, love rival)
Rin Kokonoe is the female lead in Kodomo no Jikan, and a grade schooler enrolled into Futatsubashi Elementary School. She is a deeply troubled girl who often flaunts her sexuality to express her feelings on her teacher, Daisuke Aoki. This often leads to her providing fanservice for the series.
Roku Kamihara (Rin's biological father) and Aki Kokonoe (Rin's mom) divorce after they failed to reach a compromisation when Roku insists that Aki abort Rin. Aki stands firm that she wants to give birth to Rin, and makes the decision to leave Roku. Since giving birth to Rin, Aki has raised her daughter single handedly. When Rin was 5, Reiji Kokonoe (Aki's cousin) moves into their household. Rin takes an instant liking to Reiji and she sees him as an older brother figure. Although Rin is aware of Aki and Reiji's incestous relationship, she remains close to her cousin and mother and is not disgusted by it. Rin, Aki and Reiji lived together as a happy family. Alas, good times do not last forever. Aki is diagnosed with lung cancer and her doctor suggests that she undergo an operation, even though her survival rate is only 30%. Reiji promises to earn enough money to pay for the operation fees but ultimately fails as Aki's health rapidly declines. Reiji then makes the decision to discharge Aki from the hospital so that she could live her remaining days in the Kokonoe household. Rin, convinced that she could save Aki's life by folding 1000 paper cranes, desperately folds them as she watches Aki grow paler and weaker as the days pass by. Finally, Aki's body succumbs to her cancer and departs the world with regrets -- she wanted to last long enough to see Rin enroll into elementary school. Rin then becomes traumatized and loses her ability to speak.
When Rin enrolls into Futatsubashi, Mimi Usa and Kuro Kagami, Rin's classmates, make many attempts to commute with her, but to no avail. One day, when Kuro decides to dress her up like a doll, she tries to take off Rin's shirt, provoking a frightened verbal response from her, pleading Kuro to stop. Tomoko Nogi, Rin's homeroom teacher in Grade 1, is relieved and gives Rin a warm hug, as a way to express that there is still hope in life. Since then, Rin has regained her ability to speak and is shown to be energetic and cheerful.
Rin is an extremely promiscuous little girl, with a tendency to display sexual behavior that is inappropriate for her age. Otherwise, she is a cheerful and energetic grade schooler. Rin also has a dark side -- her jealousy towards Daisuke's colleague Kyoko Hoin almost prompted her to push Kyoko off the stairs. Another instance is forcing Keito Nakamura, Daisuke's predecessor to quit his position after he verbally abused her friend, Mimi Usa.
Rin is also very protective of her friends. She is manipulative, cunning and does not hesitate to blackmail others to get what she wants.
Rin dislikes people sympathizing with her because of her family background. She temporarily distances herself from Daisuke before realizing that he genuinely cares about her as a student, and as his lover.
The relationship between Daisuke and Rin is considered to be very complex. It first ignited when Daisuke accidentally walks into his class with the girls changing on his first day at Futatsubashi. After that, during the rollcall, when Daisuke calls out Rin's name, Rin takes the initiative to flirt with him, which leaves Daisuke in embarrassment. This in turn also causes an uproar to stir in the class as Rin's classmates start teasing their hapless homeroom teacher. Later on, as Rin falls off the tree in an attempt to rescue Newman (a homeless cat that wanders in Futatsubashi), Daisuke saves Rin's life and falls unconscious. Rin, feeling indebted to Daisuke, falls in love with him. Later on, Rin visits the unconscious Daisuke in the school clinic and expresses her gratitude by kissing him on the forehead. Ever since then, Rin would unhesitatingly flirt and seduce Daisuke whenever she sees an opportunity arise. Rin would also call Daisuke by his first name outside of Futatsubashi, as her relationship with her teacher is supposed to be kept secret.
As time passes, Daisuke and Rin grow closer to each other. One day after school, Rin requests Daisuke to carry her back to the Kokonoe Household as a reward for scoring 100% on her test. Albeit reluctant, Daisuke finally confesses to Rin that he is in love with her as he carries the mischievous grade schooler in his arms.
Daisuke acknowledges Rin as his secret lover, but is constantly shown to be confused in regards to his role in the relationship, as he has never dated a girl before.
Daisuke also shows genuine concern for Rin, and even sympathizes with her when he finds out about her family background. Although that initially ticked off Rin as she hates people sympathizing with her, she falls deeper in love with Daisuke when she realizes that he is concerned about her well being as a lover. She kisses Daisuke on the lips the next day when he boldly proclaims that he is concerned about Rin as he is her lover after his home visit at the Kokonoe household.
On the other hand, Daisuke always abandons Kyoko when he hangs out with her for the sake of Rin. He also comes rushing for Rin whenever he receives distress SMS messages from her, regardless of whether or not it's a hoax.
After the Reiji House Arrest incident, Rin and Daisuke's relationship takes another step forward as Daisuke proposes to Rin, to which she accepts.
Towards the end of Rin's academic year for Grade 3, she is informed by Mimi and Kuro that the entire school knows of her relationship with Daisuke -- it is an open secret. As a result, Rin now calls Daisuke by his first name regardless of whether or not she is within school grounds.
In the series' finale, Rin kisses Daisuke again; Kodomo no Jikan concludes with the couple hugging under the starry sky.