The story begins with Hanabi, a sixth-grade girl who is neither an adult nor a child. She deals with issues such as accidentally witnessing her homeroom teacher kissing, and worrying about experiencing physiological changes before her friends. The series depicts a 12-year-old girl's innocent worries and first love.
12-sai.: Chicchana Mune no Tokimeki (Season 1)
Kiss. Hate. Love. (Episode 1)
Writer: Fumi Tsubota
Air date: 2016-04-04
Runtime: 24 min
Overview: Finally, Hanabi Ayase, Yui Aoi, Marin Ogura and the others are 6th graders! One day, the girls are talking about kissing.
Confession (Episode 2)
Writer: Fumi Tsubota
Air date: 2016-04-11
Runtime: 24 min
Overview: At Yui's household the bath broke and she has to take bath at Hiyama Bathhouse. Even though she decided not to fall in love, she starts having feelings for Kazuma Hiyama.
Double Date (Episode 3)
Writer: Fumi Tsubota
Air date: 2016-04-18
Runtime: 24 min
Overview: Yuuto asked Hanabi to go out with him. His girlfriend convinces him to take Yui and Kazuma along with them. The two couples go on a double date at the mall.
Triangle (Episode 4)
Writer: Fumi Tsubota
Air date: 2016-04-25
Runtime: 24 min
Overview: Class 6-2 has a new student: Hanabi's childhood friend who has just came back from Tokyo, who starts having a crush for Hanabi, despite seeming to be a bit of a bully.
Birthday (Episode 5)
Writer: Fumi Tsubota
Air date: 2016-05-02
Runtime: 24 min
Overview: Hanabi and Ayumu go shopping to get a present for Yuuto's birthday, after which Hanabi will go on a date with Yuuto and give him his present.
Boyfriend (Episode 6)
Writer: Fumi Tsubota
Air date: 2016-05-09
Runtime: 24 min
Overview: Ayumu tries to take Hanabi away from Yuuto. They wind up in a race. Cocoa, who wants to be Yuuto's girlfriend, decides to help Ayumu win. Can Hanabi and Yuuto discover the truth?
Beginning (Episode 7)
Writer: Fumi Tsubota
Air date: 2016-05-16
Runtime: 24 min
Overview: After Kazuma asked Yui to walk her home, she thinks what does she like him for. The answer finds it's begin in previous year...
Names (Episode 8)
Writer: Fumi Tsubota
Air date: 2016-05-23
Runtime: 24 min
Overview: Hanabi and Yui try to address Yuuto and Kazuma by their names, and to make the boys do the same. In the end, only Yui and Kazuma manage to, when Hanabi and Yuuto couldn't.
Friends (Episode 9)
Writer: Fumi Tsubota
Air date: 2016-05-30
Runtime: 24 min
Overview: Due to a misunderstanding, Hanabi and Yui fall out with each other and won't speak to each other for the next few days. In the end, Hanabi reconciles with Yui while defending the latter from other girls from another school.
The Weaver Girl and the Cowherd (Episode 10)
Writer: Fumi Tsubota
Air date: 2016-06-06
Runtime: 24 min
Overview: With the Tanabata coming along, Hanabi's homeroom teacher asked the class to write something nice about their classmates in their Tanzaku in hopes that it will strengthen the bond between boys and girls in the class.
Summer Love (Episode 11)
Writer: Fumi Tsubota
Air date: 2016-06-13
Runtime: 24 min
Overview: After accidentally hitting Yui on the head with a football during the gym lesson, Kazuma invites her to a pool date as an apology and they invite Hanabi and Yuuto.
Fireworks (Episode 12)
Writer: Fumi Tsubota
Air date: 2016-06-20
Runtime: 24 min
Overview: With Yui's cram school lessons and Kazuma's work in his family's bathhouse, Hanabi and Yuuto are left to go on a date at the summer festival.
