The episode begins with Minato and his classmates discussing why he doesn't call Mikoto "big brother," even though Mikoto is 11 months older. During lunch break, Minato realizes he forgot his lunch, but Mikoto arrives just in time to bring it to him. The classmates invite Mikoto to eat lunch outside with them, and Mikoto agrees.

A classmate asks Mikoto why he is so kind to Minato, who doesn’t even call him "big brother." Mikoto reflects on his early years with Minato. He remembers feeling overshadowed by Minato, who was a mischievous child and demanded a lot of attention from their parents. Mikoto recalls feeling neglected and frustrated, especially when Minato ruined a drawing he wanted to show their mother. During one such incident, Mikoto pushes Minato, causing him to hit his head. Their mother scolds Mikoto, emphasizing that as the older brother, he should know better. This makes Mikoto question his role as an older brother.

Hayato, their older brother, gives Mikoto a toy from the supermarket and asks him to keep it a secret. Minato finds the toy and accidentally breaks it during a scuffle, leading to a heated argument. Mikoto tells Minato that he wishes he had never been born.

Mikoto confides in Hayato about his struggles in being a good older brother to Minato. Hayato reassures him that Minato likely behaves the way he does because he admires Mikoto. Encouraged by Hayato’s words, Mikoto apologizes to Minato for his harsh words and for breaking the toy. Minato also apologizes for his behavior.

The episode ends with Mikoto helping Minato with his homework and being praised by their mother for being a good older brother. Mikoto realizes that Minato’s stubborn behavior is a sign of his affection.