Realizing that he forgot to pack his bathing suit while rushing to meet his friends at the pool, Keiichi borrows a pair of trunks from Mion's uncle, who claims that these trunks have the magical ability to make women attracted to whoever writes their name on them.

Now that she and her friends are finally free from the eternally repeating tragedies of June 1983, Rika has a new lease on life. While biking with her friends, Rika carelessly collides with an oncoming truck. When she awakens, she finds herself in another Hinamizawa.

Rika finally makes contact with Hanyu, who tells her that for her to return to her old world, she must find and dispose of a piece from her old world.

Rika becomes gradually more torn between remaining in this new world that knows no sin, or killing someone she loves and returning to her old world.

During a picnic with Keiichi, Rena accidentally swallows one of the mysterious "Fuwazaru Magatama" which falls from the sky, and begins acting lovesick.