Anime and Manga Mature (18+) 

Berserk

by Kentaro Miura

Set in a fictional medieval Europe, follow Guts who seeks to have revenge on Griffin who betrayed him. Guts uses a large sword called Dragon Slayer.

Dandadan

by Yukinobu Tatsu

A high school girl who believes in ghosts and the supernatural get abducted by Aliens and then discovers she has psychokinetic powers which allow her to visualize peoples auras, she can visualize a giant hand to control those auras.

Elfen Lied

by Lynn Okamoto

Lucy a teenage Diclonius girl, escapes her captivity (all diclinous are locked away and studied). More Diclonius girls are sent after her to recapture her. Lucy wants to keep her freedom but at what cost.

Hell's Paradise

by Yuki Katu

Set in the  Edo period of Japan, a select group of convicted criminals who are awaiting execution are offered the chance of being pardoned and freed but need to investigate an island recently discovered in the southwest of the Ryukyu Kingdom.

Platinum End

by Tusugmi Ohba 

Follow the story of Mirai Kakehashi who tries to commit suicide but is recused by his guardian angel called Nasse. Nasse vows to protect him and also gives him special powers as he is one of the chosen 13 individuals chosen by different angels to take the role of God who is retiring in 999 days.

Tales of the Tendo Family

by Ken Saito

Masato, a son of the Tendo family, is meant to marry Hojo Ran, the daughter of a baron. There's just one problem: she's a fake. The real Ran has fled after hearing that few make it out of the Tendo family alive. In her place is a young woman who says she will die if it means saving someone else's life.