Oniisan, a typical salaryman, has the weekly duty of protecting high school student Ai-chan from gropers by escorting her during their Monday morning train commutes. Despite the short time Oniisan and Ai-chan spend together, they manage to bond and learn more about each other's lives. To help Oniisan get through his Monday blues, Ai-chan gives him small presents as motivation. Ai-chan and many other girls—who all share a certain attractive trait—lighten up the Mondays of their male friends and colleagues for the long week ahead. The anime follows a salaryman who has a chance meeting with a girl named Ai on the train. They begin to meet every Monday on the train, with the man serving as her bodyguard on the crowded commute while they chat.
