If Today was the Last Day

An island in Japan is the site for the dumped and the refuse. Nanakusa and Yu who were childhood and school friends meet on this island that is called Kaiden, a scary name that only refers to things not normal or earthly. The reunited friends strike a bargain and are soon involved in cases most would not dare be involved in or become entangled in.

An executive of the yakuza osako clan leaves the underworld to raise his only son, but a war between the "Kaiyama" clan brings him back.

A single mother was murdered in a room in an apartment while the news of an indiscriminate murder of women was making headlines every day. At the same time, Kazuki Saito, her son, disappears. The public speculates who could be the culprit and they even have a type, and the police are also looking for him. Meanwhile, a girl named Sayo, wanders into the woods and meets the speculated culprit with a knife. What is the fate of the girl who met the murderer?