Ten-year-old fifth-graders Akira and Koichi are best friends who always seem to get into trouble. When the new term starts, they are placed in different classes. Initially, this is just a minor obstacle to their continued friendship, but then their relationship begins to change. Akira befriends the fatherless Shun, while Koichi hangs out with the newly-transferred and mischievous Samajima. One day, when Akira declines an invitation to attend Shun's birthday party in favour of spending time with Koichi, tragedy strikes as Shun dies along with his mentally ill mother. Koichi and Samajima become engrossed with committing petty crimes.