To Me, The One Who Loved You + To Every You I’ve Loved Before (Light Novel) by Yomoji Otono

A heartrending tale of star-crossed young lovers and parallel worlds!
In Hidaka Koyomi’s world, travel between slightly different alternate universes is commonplace. After his parents’ divorce, Hidaka now lives with his father. One day, he falls in love with a girl named Satou Shiori after meeting her at his father’s workplace. Unfortunately, their young love seems doomed as their parents are getting remarried…to each other. Is there some parallel world out there where these two can be together as lovers, not step-siblings…and what could be the price if they try to find out?

To Every You I’ve Loved Before and To Me, The One Who Loved You are parallel universe novels by the same author and released on the same day. They can be read in either order to complement each other.