Momoko, who attends a special school, is both mentally and physically disabled. Every morning she becomes peevish because she can't go to the ordinary school with her twin brother Riki. Her family soothes Momoko by singing her favorite song "The Song of Frogs." One day, Momoko shouts encouragement to Riki who's playing dodgeball at an open classroom day and Riki's team wins the game. Ryuji, whose team lost the game, is not impressed and demands that Riki stop bringing his 'idiot sister' to school. Riki totally loses control and hits Ryuji with all his might. The following year, an experiment in integrated education is implemented and Momoko begins to attend Riki's school. Unfortunately, her physical condition takes a turn for the worse and she's sent to a hospital. Riki and all her classmates want to cheer her up and they set a goal of winning a relay race so that they would be able to tell Momoko the good news. Meanwhile, the fastest sprinter, Ryuichi, insists that he won't be taking part in the race.

The third season of Kimi ni Todoke. What do you do once you're a couple? Although she struggles with her blossoming feelings, Sawako comes to terms with herself and tells Kazehaya how she feels about him. Attracted by Sawako's unnoticed efforts and genuine personality, Kazehaya also candidly makes his feelings known. Thus, their new relationship begins. Their first date, their school life together, joy, embarrassment and new struggles — everything is fresh and new as the couple awkwardly and gradually learns more about one another, all while their friends' love stories begin to take shape as well. This bittersweet and poignant story of young people, woven from their romantic feelings and dear friendships, begins once more.

Tsubomi Tachibana is a fifth grader dealing with rather sensitive issues such as her mother's pregnancy, her first period and the strange feelings she has started to get when she has been around boys.

Harada Kusuko is a high school girl with a secret crush on the class playboy, Mishima Takeshi. After breaking up with his most recent girlfriend, Mishima asks Kusuko to be his date for the class trip to Kyoto. She's over the moon, but in fact, Mishima is hung up on Shouko, his middle school teacher. Despite the age gap (and general inappropriateness of the relationship), Mishima still sees Shouko, whose marriage is disintegrating. His friend and loyal wingman, Kotaro, openly disapproves of this connection. As the emotional tensions mount, Mishima becomes involved in fights with other boys, and eventually, he's expelled from school. Feeling like he's been a complete jerk, Mishima breaks up with Kusuko and drops out of her life. Will true love find a way?