If you liked
Karas
|
...then you might like
Garo: Honoo no Kokuin
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Garo was inspired by Karas. They both feature a special being who summons/turn in a specific metallic gear which is connected to the non-human realm, and in both protagonists use this superpower gear to kill demons.
If you liked
Naruto
|
...then you might like
Jujutsu Kaisen
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A red-haired protagonist, with an evil being inside him, who grants him more power and tries to overcome his consciousness. So this protagonist fights with bad guys/curses. There's an ongoing bromance and rivalry with a cool dark-haired guy, and a senior white-haired guy with face covered by mask (but the masks are in reverse). And many charismatic supporting characters.
If you liked
Tokyo Ghoul
|
...then you might like
Jujutsu Kaisen
|
In both, the protagonist deals with an unknown demonic being inside his body. And constantly (based on the OP) decides a dilemma if he's a good or bad guy after all.
If you liked
Let Dai
|
...then you might like
Dog Style
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Although Let Dai's genre is shounen ai (no sex shown) and Dog Style is yaoi (sex is shown quite explicitly), both are about gay highschool delinquents, and both deal with loneliness and finding a soul mate. Both are bittersweet. Both show rape at some point, though In Let Dai a whole plot line is drawn out of it and it ends much more tragically. In the end, both mangas have a somewhat similar feeling about them. Both are good reads and pleasent to the eye.
If you liked
C: The Money of Soul and Possibility Control
|
...then you might like
Persona 4 the Animation
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Although these series are quite different in their mood and idea, they share the following two things: (1) Protagonists in both series get in a mysterious parallel world and fight there using powerful "familiars" (actually, they're not usual familiars, but explaining them would be a spoiler, so let's leave it at that). The reasons for fighting and effect of the battle outcome are really different, but the process is pretty much the same: the familiars combat under their owners command invoking different technics and weapons, and that makes a really nice and impressive action. (2) There is a mystery that protagonists are trying to figure out in both series.
If you liked
Angel Beats!
|
...then you might like
Kore wa Zombie desu ka?
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They give out the same feeling. They both have really good somewhat crazy humor moments, and touching moments, too, while the overall plot is poor and one can hardly speak about the whole anime story development. Kore wa Zombie Desu ka? and Angel Beats are similar in this: they're not your usual episodic anime and it seems like there's a story that progresses from one episode to another, but in reality it's only a ghost of the story that only takes place to move the anime on and to connect those funny and sad moments. And it'll be fair to say those moments are nice to your eyes. And yeah, as it was already mentioned in other recommendations, both these anime play with the undead theme.