The members of a sci-fi club accidentally spill Coke on the remote controller of an air-conditioner during summer and suddenly a time machine appears in their sweating bath-like clubroom.

Momotaro and Hidemaro are 1st-years at Otokojuku, a private boys school where true men are made. Momotaro, proficient in academics and martial arts becomes good friends with Hidemaro an underachieving weakling. Omito Date, former student leader, plans his revenge against his former school. Now leader of an evil army from rival Kanto Gogakuren school he fully intends on taking over Otokojuku.

Tamako is 20 years old, lives at home with her mother (Kishimoto Kayoko) and teenaged brother, and simply refuses to grow up. Ever since her father left the family, she's stopped trusting people, and now lounges around in her own small, claustrophobic world. Wearing an iron helmet whenever she steps outside, she ventures only to her mom's beauty salon, the mechanic shop, and the bakery - the source of her greatest joy in life, sweet buns. Her world is static, insular, and safe, and there's no need to change - that is until her cat runs away, the bakery closes, and her mom falls in love with another man.

Mitsuko Murakami puts the passion to balloon in the hot-air balloon Circle "Airheads". The club gathered young people holding a variety of thoughts. But "Airheads" is disbanded not too long. Five years after their time in the Balloon Club ended, the members' former club leader brings them back together and rekindles old flames.