 If you liked
Iris Zero
|
 ...then you might like
Aku no Hana
|
While both series aren't on the same level of psychological tendencies, they both have bits of that background.
Both series also takes place at a school life setting where the main male character meets another popular female character. However, between the two of them, they often deal with strange circumstances.
There is also somewhat of a 'love triangle' although it's played as less dramatic but rather in a more psychological way in both series.
In general, both has a more serious tone than traditional romance manga titles.