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

Komori Hiroto is a kind young man who works at the city hall. Since losing his parents in an accident, he has been living with younger brother Michito, who has autism spectrum disorder. Their restful days are changed when they meet a young boy called "Lion" who they decide to take in. Before long, they get caught up in an incident that changes their lives completely.—Drama-Otaku

Hiroto, a kind and earnest older brother and his autistic younger brother, Michito, led an ordinary life together - until one day, a five-year-old boy appeared at their doorstep claiming to be their nephew. This boy, who refers to himself as "Lion", says he is the son of Hiroto and Michito's sister, who they believed was dead. However, she was actually alive only to vanish again, entrusting her young son to the brothers' care. The trio develop a strong camaraderie as they seek to unravel a thicket of lies and a grand scheme of love, surrounding the mysterious sister.—TBS Program Catalog