Some details I recall about it was that the main character was a female in middle school.

One of classmates is named Marisa. Another one hung out with college kids and had an abusive home life and I think she was either bullied or blackmailed into suicide. One kid was a boy and he was nervous about being caught helping the main character and had 2 younger siblings and lived with an aunt or grandma. He eventually vanished from the plot "mysteriously." People in their class were getting killed off one by one and eventually the class was disbanded and forced to go to different schools and the kids were considered cursed.

Thanks for your time!

Found it!

I read this like 2/3 years ago. I hope its done by now.

https://www.mangaupdates.com/series.html?id=105505

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