The Stranger by the Shore

Yuna Ichihara's spring break is far from pleasant, especially after she sends off her best friend Sacchan, who is moving away. But while heading home, the timid girl brightens up when she encounters a boy who looks exactly like her first love—a prince from a shoujo manga. Subsequently, she finds herself in a peculiar situation with the mature Akari Yamamoto, a new neighbor who immediately befriends her. Now attending the same high school together, Yuna shows interest in Akari's brother Rio—the same mysterious and handsome boy she met during spring break. Likewise, Akari is falling for Yuna's carefree childhood friend, Kazuomi Inui. However, love is not at anyone's fingertips, as the relationship between these four contrasting friends faces complications, preventing them from moving forward. To discover the truth between them, they will need to confront their own struggles and uncover secrets hidden among themselves.

While struggling to make friends after his parents’ divorce, Koyomi Takasaki meets Kazune Takigawa, but apparently, they already have. Kazune reveals that she’s from World Line 85, an alternate universe in which she and Koyomi are lovers. But in a reality where moving between dimensions is natural, could Koyomi be the one from another world?

Koyomi Hidaka and Shiori Sato meet at his father’s research center and begin to fall in love, but so do their parents, who eventually marry. To avoid becoming stepsiblings, they decide to run away to a parallel universe. Traveling between dimensions is common in their world, but not without repercussions. Does a universe exist for the young couple, and what will it cost them to find it?

The story centers on a boy named Kazuki Tsukigase, who transfers to a high school on a remote island to get away from anyone who knows him. Kazuki finds out that there is an inlet on the island where people are rumored to disappear. Exploring the inlet, he encounters an unconscious girl. When she comes to after Kazuki takes her to the clinic, she is unable to give out anything about her identity except that she is named Nao, is 16 years old, and whispers the year "1974."