Foster Plus Co.

High school student Naotatsu travels to live at his uncle's house. In the pouring rain, he is picked up at the nearest station by a strange adult woman named Sakaki who guides him to an unexpected share house where a life together begins.

Female students, including Hikari Tomonaga, from a high school cheerdance club follow strict instructions from their teacher Kaoruko Saotome. They compete at the USA Cheerdance Championship.

Hibiki Shimada, a normal 17-year-old high-school student, still does not know how to fall in love—although surrounded by love "experts"—until one day she realizes she's fallen in love with her hot and nice 26-year-old teacher, Itō. She then takes a path to make her teacher understand how she feels for him.

Set in post-war Okinawa, Japan, Gusuku had 3 close childhood friends: On, Yamako and On's younger brother Rei. On was the oldest of the group and he was like a leader to everybody else. He was also a heroic figure to them. On led his friends into the U.S. military base and they stole supplies to give away to the local residents. Everybody in the neighborhood praised On. One night, they entered the U.S. military based to steal supplies. During their raid, On was chased by U.S. soldiers and went missing. Years later, Gusuku now works as a police officer. Yamako is an elementary school teacher. Rei is a member of the yakuza. These three people are still unable to get over the disappearance of On. They chase after the truth behind On's disappearance and uncover a shocking answer.

Story takes place 2 years after "Chihayafuru Part 2" and Chihaya is now a high school senior.