If you liked "Karneval"
...then you might like

Title: Pandora Hearts
Type: Anime/Manga
Original Creator: Mochizuki Jun
Genres: Adventure, Fantasy, Shounen, Supernatural
Summary: Oz Vessalius, heir to one of the duke houses, has just turned fifteen. His life is rich and carefree, darkened only by the constant absence of his father. At his coming-of-age ceremony, however, everything changes. For no reason that he can discern, he's cast into the prison known as the "Abyss", only to be saved by a "chain" known as Alice, the bloodstained black rabbit. It is unknown why was he cast into Abyss, how does Alice factor into it all, and what does the organization known as "Pandora" want with him.

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If you liked "Karneval"
...then you might like

Title: D.Gray-man
Type: Anime/Manga
Original Creator: Hoshino Katsura
Genres: Action, Adventure, Comedy, Demons, Shounen, Super Power
Summary: Towards the end of the 19th century, Allen Walker officially joins the organization of Exorcists that destroy the beings known as Akuma; mechanic weapons made by the Millennium Earl with the suffering souls of the dead. Allen has both a cursed eye and an anti-Akuma weapon as an arm, bearing the power of "Innocence", a gift given to him as an apostle of God. Allen, along with his fellow Exorcists must put a stop to the Millennium Earl's ultimate plot that could lead to the destruction of the world and all who live on it.

Source: link