Nida is a single mother who takes care of her anti-social son who has locked himself in his room for five years. The only way to communicate with her son is to write on a piece of paper and slip it under the door. But, when outsiders start to get curious about what is going on behind the door of her son's room, a series of terrible events starts to happen.
Matteo has decided not to go to school anymore and stay at home instead.
Drama is based on series of mystery novels by Sakaki Tsukasa - "Hikikomori Tantei". Torii is a hikikomori who can make deductions even when he's given very small amount of information. His friend Sakaki works in insurance company and he's the only person who can help Torii to break out of his hikikomori style. They begin to solve mystery cases together.
