Small but worthy SPOILERS for those who want to dive in this manga (its worth it)
The description makes it seem that there is some age gap romance and yandere involved, there is not, this manga is about a girl that can see trough peoples mind and see what crimes they have commited, ending with her somehow indirectly killing them, that (hinted to be) pedo teacher is just one of the many arcs of the girl seeing past murders he commited, said arc ends by chapter 4 and we get even more interesting arcs from there onward
In fact, if you pay close attention, chapter 1 to 3 foreshadow much of the girls flaw, (example from that one part where she didnt knew that the poision the teacher is using was odorless, She isnt a real detective with or without her powers, plus that one basket segment with her bully) and maybe some of her qualities, for when she really seem to have compassion and empathy for the girl that survived the teachers kidnapping at that one thought bubble (such girl would be her bully, but thanks to her power she might truly know how good hearted that girl is)
Most importantly, we dont know if she will turn kira or she has good ideals for doing her vigiliantism, the author is very good at subverting expectations, and ultimately pretty talented, even if i already see what his stance about her vigilantism is, (at one point the girl is refered as a "monster", now, AT THAT POINT IN THE HISTORY AND THUS FAR BY RECENT CHAPTERS, in my opinion its a very unfair and ignorant stance, but it made sense from who that comment came from)
All in all, read the manga, and the description dosent do much service