The appearance of a mysterious little boy interrupts the quiet, predictable life shared by an artist with autism and his caring older brother.

Ryuhei Agawa is a 25-year-old soba restaurant owner who has been in love with his neighbor, Tamaki Murashibara since he was a child and is always dejected when Tamaki only sees him as a "younger brother". However, the appearance of a love rival starts to ignite Ryuhei, making him determined to end his unrequited love.