 If you liked
Nazo no Kanojo X
|
 ...then you might like
Kuzu no Honkai
|
Both anime have kinda "agressive" romance.
Nazo is maybe more specific than Kuzu.
While Kuzu no Honkai (10/10) is much darker than Nazo no Kanojo X (10/10), they are similar in some ways:
Both have kind of a forceful/aggressive romance relationship.
Both female MCs are cute and weird at the same time and they also have dark and short hair.
Both have an interesting (uncomfortable for some) concept.
Both are Seinen and are not for kids (+17).
Both are School and Slice of Life.
Both have a dark vibe. While Nazo no Kanojo X's ambiance may not seem like it, some find the repeated sunset, night, rain and dream scenes in it kind of dark.