Yotsuba starts wanting to die, wishes she was never born, tries using the clover. Uichi hears this.
While fighting over the clover with Uichi like Gollum and Frodo, Yotsuba goes back in time again to when she is a child. Uichi loses, Yotsuba wins. Yotsuba keeps her memory, Uichi forgets. She refuses the fork-in-road path to play with Uichi. Jumps from the roof and commits suicide to make everyone happy. Time passes until high school, everyone living well. (Except Yotsuba, she's cosplaying Rebecca from Edgerunners.)
Uichi pricks his ring finger where clover ring was during high school, partially recovers his memory, crashes out. Involves Futaha, who somehow flies across logic and tells him "he's in a time loop". Tada, recalls everything. Somehow breaks all prior plot precedent and "magically" finds the 4-leaf clover in the field in front of the shrine, and goes back as a child AGAIN.
After final loop, through power of friendship (and social media), they get her mother arrested.
They confront Futaha about her true personality, convince her with a letter / montage of predicted events. 3 kids somehow reconcile Futaha's parents marital problems like Dr. Phil. Futaha's parents cooperate in the plan.
They go to the cops. Cops and politician leaders are corrupt part of the Society, refuse to investigate. Then kids stage a social media smear campaign. Somehow convince the world to stage mass protests Animal-Farm style, "Pink Lady Bad". Then a livesteam battle occurs (?) between Uichi 10yo, and a 30yo woman in her basement. A child's tears saves the day...?
Yosuba's brother goes double-agent and provides the lynchpin testimony when actual investigation is forced. Lampshaded security protocols of police literally putting a coth over their head when interacting with her in the jail cell. The mother freaks out that nothing is working, starts sobbing uncontrollably about not seeing "beautiful faces", then sees her own reflection in the mirror. Becomes entranced with it like a demon from Constantine.
Ends on a happy-go-lucky everyone is back in highschool note closing with the tagline phrase. The end.