An MSDF submarine collides with a U.S. nuclear submarine, crushing all 76 people on board, including its CO, Shiro Kaieda. However, the crew survives. The accident is a cover story to get the MSDF submarine's crew on board the Seabat, a nuclear submarine secretly built by the Japanese and U.S. governments. However, Kaieda loads the Seabat with nuclear missiles and suddenly mutinies and flees.

After graduating from high school, Sota Koyurugi studies bakery at an institute. In high school, he fell in love with beautiful Saeko. Because of Sota's effort, he is able to have a romantic relationship with Saeko right before Christmas. Saeko though tells Sota that she will be unable to meet him on Valentine's Day, but can meet him on the day before Valentine's Day. On that day, Sota gives Saeko chocolate that he made, but she doesn't accept his gift. Saeko tells him that she didn't think they were dating. Sota is heartbroken, but he doesn't give up hope.

To make Saeko love him, he travels to France with little money and studies chocolate there. This is because Saeko loves chocolate. 5 years later, Sota becomes a first-class Chocolatier. Now back in Japan, Sota opens his very own store.

The story follows Aya from the time she moves to Tokyo at age 23 up until she turns 40. Aya has to adjust to the different values and perceptions of the big city as she struggles with challenging situations. We get to follow Aya’s move from one neighborhood to another as she maneuvers her career and love life.

When a classically trained young conductor meets a free-spirited pianist at music school, their romance and their music have a hard time harmonizing.

Follow the life of Michiru Aida, a beauty parlor assistant who returns to Tokyo after 4 years. Bullied by her seniors at work and abused by her boyfriend, she is reunited with her best friend during high school, Ruka Kishimoto, a skilled motocross racer. Takeru, a make-up artist, is introduced to Ruka by her housemate, Eri and thus begin a journey of friendship.