Manga about adults going back in the past to high school

Thanks for the suggestion! Although none of the recommendations (at least in this website) look like the manga I’m looking for.

Some other details I remember is that the manga was in black and white (unlike ReLIFE). It also seemed fairly short when I originally read it (something like 12 chapters maybe?), but that could’ve changed. The characters also had generally normal looking hair, not too crazy like some other anime and mangas.

This may not help but I do remember the group that traveled back in time ended up having some sort of meeting in a classroom (I’m assuming after hours) and discussing how they were back in high school and how they would handle this situation.

I also think that in the beginning of the manga everyone that ended up traveling to the past actually meet up when they were still adults the day prior. The “time traveling” happened (or seemed to happen) when the characters went to sleep. When they woke up, they noticed they were there younger selves.

I’ll keep searching.