Civil servant Komori Kohito (Yagira Yuya) lives a peaceful life with his younger brother Komori Miruto (Bando Ryuta), who has autism spectrum disorder.Since the early death of his parents, he has always followed his younger brother's daily routine, getting up and going out at the same time, and after finishing work, he went to pick up the beautiful girl to go home.Just like this day after day, one day——

A boy who calls himself “ Lion ” (Osora Sato) suddenly appears in front of the brothers.

Americans are thrown into panic when a lion breaks into their home and claims it wants to live there.In order to help his younger brother Miruto, who is having difficulty adapting to the changes, and to resume his normal daily life, Miruto considers sending the boy to the police station.However, the mobile phone handed over by the lion received a message from an unknown sender, which said “I will be looking after you in the future”. This message reminded Jinren of a forgotten person——

In addition, at a certain moment, Jinren accidentally discovered bruises on the lion's body.

At the same time, in a certain county, Shogo Tachibana (Ri Mukai) is anxiously filing a missing persons report.

This incident gradually aroused heated discussion in society as a “missing mother and child incident”——

Who abandoned the lion?Who is the lion?——

The people of Gu and Meilu, who were confused by the sudden arrival of the lion like a storm, gradually became closer to the lion, and their relationship also changed.This warm suspense drama depicts people struggling to survive in order to protect precious things no matter what kind of predicament they are in, and shows family love and brotherly love. Now it has officially begun!