The series revolves around the Mizuki Diving Club (MDC), which is on the verge of closing down after having financial troubles. The club's new coach persuades the club's parent company to stay open on one condition: that the club sends one of its members to next year's Olympics as part of Japan's Olympic team. (Source: ANN)

The Persona Century Corporation has purchased nearly every parcel of land on earth. Dissension is not tolerated within the corporation's borders and those who oppose Persona are dealt with swiftly. Of those few places not yet under Persona's control is the free town of Kabuki-cho, also known as "The Dark Side of Tokyo". Within the town, under the leadership of a woman named Mai, is a small resistance group called Messiah. Into this world steps a man who takes the sobriquet of Kabuki-cho: Darkside. Sealed up in another dimension eighteen years ago by Persona Century, Darkside now returns to aid Messiah using his unique mystic power of renewal.

Alka is an assassin for the Clan of the Sword. She's on a journey to find the woman Jin Valel, who killed her master Hon without feeling—not unlike how Alka has learned to kill in her work as an assassin. On her journey, Alka encounters three strange women, each a great warrior in her own right and grapples with her slain master's wish that she leaves the life of an assassin behind. (Source: ANN)

Long ago, the gate to the world of darkness was sealed. Now evil warriors, known as Remnants, are trying to reopen the gate and let demons take over the world. However, at Tobira High School, there exist guardians of the gate who must risk their lives to prevent the gate from being opened.