If you liked
Ao no Exorcist
|
...then you might like
Exorcist wo Otosenai
|
Both are action manga that follow the theme of exorcists and demons.
If you liked
Bastard
|
...then you might like
Killing Stalking
|
Both have dark atmospheres, though Killing Stalking is much darker. Also, the main characters are troubled and they find themselves forced into situations with people who are much more messed up than they are. There's somewhat of a recurring theme of love in both series. This includes the presence of love, ways of showing love, and complete absence of love. Neither series is too heavy on the love though. Just read it for the psychological themes.
If you liked
Devils Line
|
...then you might like
Tokyo Ghoul:re
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Devil's Line is based off a manga, just like Tokyo Ghoul Re, where the main character struggles to control the impulses and thoughts that come with being who they are. Both series are psychological but Devil's Line is more of a romance while Tokyo Ghoul is more action. Also, both are seinen series so there are some mature themes... So, yeah, Devil's Line is worth the watch if you like anime similar to Tokyo Ghoul but with more romance.
If you liked
91 Days
|
...then you might like
Hakata Tonkotsu Ramens
|
Both anime include revenge as a plot point. For Hakata Tonkotsu Ramens, it's relatively short since the series is pretty episodic. If you want to see a whole story of revenge, then 91 Days is the anime you want to watch. Also, both give off a similar vibe. They take place in different time periods, but both have a 1920's-1940's feel with the mafia (from 91 Days) and the hitmen (from Hakata Tonkotsu Ramens).