 If you liked
Sankarea
|
 ...then you might like
Nazo no Kanojo X
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Supernatural fills the void for both of these series.
In both anime(s), there is the female lead with a mystery. The MC of both series becomes friends of them and learns more about their character. Incidents happen and events foretold as episodes progresses.
There is comedy, romance, and a source of mixed in mystery about the main plot. Both series also takes place in a school-like setting.