dead mom alert!!!! theory time!
so the uncle was transferred in around when the teacher died. Was it because
1. he was involved with the Gemini coverup and got sent away to stop being an embarrassment
2. he was planning to do this for a while to get an opportunity to research her sister’s death
and with regards to tsumugi
1. is it time to team up with murder boy to hunt down the mom’s killer
2. tsumugi said that she wasn’t a good girl. THE MOM WAS A SERIAL KILLER AND TSUMUGI OFF’D HER
with regards to tahakaru, his obsession with murderers could be because
1. it's his coping mechanism to try to understand what took away his mother
2. it's his coping mechanism to try to understand his mother
personally I'm leaning towards uncle being guilty of a coverup, and only investigating this case to get back at what got him into trouble and as an achievement to help him worm his way back to central, the dead sister seems like the type of misdirection the author likes to use.
either way, poor tahakaru tho. no way he's getting out of this without a few good traumas