さかさまクランベリー

Meguru Kayano, a middle schooler with a strong brother complex, has never considered romance with anyone but her beloved sibling. But one day, after a freak accident involving an accidental kiss with her classmate Takahi Aoyama, Meguru blacks out and wakes up two years in the future—where she's shocked to find herself dating Aoyama, now a tall and handsome version of the boy she once bickered with. To return to her own time, Meguru must kiss him again, but the journey to undo the time slip forces her to confront her feelings and the unexpected bonds that have formed. (Unreviewed summary by Grok 2)