Imamura Kinichirou, a high school senior, prepares to graduate with no friends and having never participated in extracurricular activities. An accident on the last day of school somehow sends Imamura and Akira Fujieda, a popular girl in Imamura's graduating class, back in time to their first day of high school. Imamura seizes the opportunity for a second chance to improve his high school life, and joins the school's troubled ōendan club.
The protagonist of the series. Assumed to be a delinquent by his classmates because of his appearance, he was a loner throughout high school and joined no school clubs. On his last day of school, he recalls a memory of the captain of his school's now-defunct ōendan singing the school anthem. He attempts to break into the club's former office, though he instead falls down a flight of stairs and wakes up three years in the past, on his first day of high school. Recalling how the ōendan club was disbanded during his time in high school, he joins the club and vows to save it.
Akira Fujieda (藤枝暁,Fujieda Akira)
A popular girl in Imamura's class. She witnesses Imamura breaking into the ōendan's office and assumes him to be a thief, but falls down a flight of stairs when running to seek help. Like Imamura, she is sent back in time to her first day of high school.
Yoshiko Usami (宇佐美良子,Usami Yoshiko)
The captain of the school's ōendan. She is the sole member of the club, having driven away the other members with her stubbornness and extreme work ethic. When Imamura joins the ōendan, he helps her to regather the club's old members.
Tamaki Abe (安倍珠貴,Abe Tamaki)
The captain of the school's cheerleading squad. She greatly despises the ōendan, believing them to be old-fashioned.
The school's guidance counselor, and the ōendan's faculty advisor.