Sixteen-year-old Yuuki Hase finally mustered the courage to approach his crush, Kaori Fujimiya, and ask if she would like to be friends. Despite her aloof personality, he was not prepared for the brusque rejection she gave him, which was identical to how she rebuffed everyone else. One day, Yuuki stumbled upon Kaori having lunch alone on the roof, where she usually retreated during break time. He started meeting with her there every day, hoping to understand her better. As time passed, she began to open up, but towards the end of the week, she shut down again. Yuuki discovered that the reason for her sudden coldness was an accident in middle school that caused her to forget everyone close to her, except her family, on every Monday. Terrified of hurting others, Kaori stopped making friends altogether. Yuuki, however, refused to be just a temporary friend. Every Monday, he persisted in asking Kaori the exact same question: "Would you like to be friends?" He understood that deep down, Kaori longed for a true friend.