One day, Zhang Chulan is attacked by zombies in a graveyard. In the midst of that situation, he saves the life of a girl, throwing the kitchen knife in his hand in order to kill the enemies. The girl tells Chulan, who is relieved, to face his hardships head on and leaves. However, Chulan later sees that girl again at his university. From that moment, Zhang Chulan's destiny begins to move. There will be strangers with special powers appearing one by one, with battles involving those abilities. Each episode will bring a new mystery to light.

[Source: MyAnimeList News]

In the first season, the protagonist, Chou Soran, hiding that he is an “outsider” (someone able to use special abilities) encounters a mysterious girl named Fuu Houhou who holds the secret of eternal life.

Together, they will enter the Raten Tournament where they will try to solve the mysteries related to them.

The second season marks the beginning of the fighting tournament between Outsiders while mysteries will gradually be unveiled and new characters will appear.

[Source: Crunchyroll]

Third season of Hitori no Shita: The Outcast.