A young man who suffers from guilt related to his adored sister's death encounters her ghost in a haunted tunnel. He makes repeated visits to the tunnel and re-experiences the past.

The story takes place during a summer of continuous sunshine when water supply restrictions are issued in the city. Shunsaku Iwakiri works for the city's water department and his job is to visit homes and stores that are behind on their bills and either collect the money or shut off the water supply (water suspension enforcement). Shunsaku is separated from his wife and children, and his heart grows thirsty as he spends his days visiting poor households and being abhorred. One day, during a water shutoff, Shunsaku meets two young sisters who have been neglected. He sees them as his own children and offers them a helping hand.

In a coastal town attracting artists, 14-year-old Sosuke and his friends stay busy painting and helping with school projects. As carefree children interact with secret-laden adults, the sunlit ocean reflects their contrasting struggles—kids embracing challenges while adults seek elusive answers.

Makoto is a student at an art university. She was once captivated by her art class teacher, Ira when she was just 12 years old. Ira vanishes from the scene and, not until six years later, appears before Makoto at an art exhibition. Surprisingly, she looks the same as Makoto remembered and has a secret to hide. Although still human, Ira seems to have a thirst for blood.

When a private detective is murdered, a former colleague and a trainee detective are sent to investigate. Along the way, they uncover a tragic truth that triggers memories from their own haunted pasts.

Akiko, a girl living a hard life after her father passes away and her mother's new boyfriend turns abusive, starts receiving encouraging letters from her 30-year-old-future self. Akiko also starts to get bullied in school, and her teacher Shinomiya tries to help her, but ends up losing her job. Akiko also unearths a story written to her by her father, telling her how he originally met her mother, who was the abused daughter of a politician.