[Natsuzo] A story about how I became a woman due to TS disease and, as a prank, made my friend lose his virginity, but then couldn't turn back

After a mysterious TS-related transformation leaves one friend unable to return to his former body, a prank intended to make the other lose his virginity spirals into a charged lesson in teasing, desire, and awkward intimacy. The now-female protagonist, newly curvaceous and conspicuously well-endowed, matches her friend’s nervous curiosity with bold confidence as kissing gives way to increasingly explicit encounters. Their playful protests and unfinished confessions keep the mood mischievous, yet the irreversible change and unspoken attachment make the joke feel increasingly like a relationship neither of them wants to name.