A newlywed couple move into an apartment near the Sumida River in Tokyo. Tezuka Nana (Harada Tomoyo) is a designer of sportswear. She was pursued by sports gym trainer Shota (Tanaka Kei) whom she met through work and they got married despite their 15-year age gap. What they share in common is a love of mysteries. Seeing the close families and couples, they imagine a bright and happy future for themselves. However, the fates of the Tezukas are rocked by a residents meeting that Nana attends. The residents of the apartment building start dying around them. Those with motives to kill have alibis and the murderers cannot be arrested in any of the cases. The riddle lies in a game that the residents are playing among themselves. 13 of them have written down the people they want to kill for offending them and started this murder game where these slips of paper are randomly drawn. At first, it was something that none of them took seriously. Then the people whose names were written started getting killed one after another and another threatening note is delivered with the warning, “You are next”. There is no turning back even if they have regrets.