To Me, The One Who Loved You

From Seven Seas: In Koyomi Hidaka's world, travel between slightly different alternate universes is commonplace. After his parents' recent divorce, Koyomi lives with his father and falls in love with a girl named Sato Shiori when they meet at his father's workplace. But their young love seems doomed when their parents get remarried—to each other. Is there some parallel world out there where Koyomi and Shiori can be together as lovers, not step-siblings...and what could be the price if they try to find out?