My guess is the landslide happens on the first day, or day before the first day of the loop, then the loop starts and Hasumi is barely clinging to life in the hospital bed until she dies. The calendar on page 10 shows it's saturday, then when the reset happens it's back to wednesday. So Ena was reborn on saturday, paired with Sae as mentor, got put through the whole day, had their fight and the curse locks everyone into the loop and sends them back to wednesday.
Hasumi was never in the hospital—the hospital had no patient by that name (
ch. 14 p. 28)—that was a lie Sae told everyone (
this ch. p. 24) and that Ena has maintained. She actually died during the landslide and was reborn Wednesday (
p. 5).
unless i missed something, sounds like Hasumi died in the landslide (but also is in the hospital???), the whole class moved on, Sugimoto died being killed by another girl, became Sae the cupid, went back in time and manipulated the situation to make sure Hasumi die, and then became Ena. That's really confusing lol
Sugimoto didn't go back in time then. She died, became cupid Sae, and at some point infiltrated this class for an entire year to pair students up as she saw fit—bullying
Hasumi on the side. I don't think she
purposefully manipulated the situation to get
Hasumi killed, but she did nothing to stop the unnecessary and dangerous search for her—triggered only because Sae went "missing"—and didn't care that this got
Hasumi killed. I think it's a callous disregard for human life rather than a master plan.
But then,
Hasumi became Ena so Sae picked her up immediately to keep control of her. This mentorship was all at camp and lasted only for those few days before they both snapped and Sae cursed everything into the loop. Seeing how skilled Ena is now, she must have been
Groundhog Daying it for a long time since then.