Isekai Shoukan-sareta ga Kyousei Soukan-sareta Ore wa Shikatanaku Yaseru Koto ni Shita.

Haruhiko is a thirty-two-year-old recluse whose life has been defined by isolation and his considerable weight. His mundane existence comes to an abrupt halt one night when he is struck by a bus, only to awaken in the midst of a magical summoning ritual intended to pull him into another world. However, the fantastical transition does not go as planned. The otherworldly summoning system encounters a critical error due to strict weight limitations, rejecting him outright and forcibly returning him to his own home. The failed summoning leaves behind an unexpected complication: a princess from the fantasy realm has accidentally crossed over alongside him during the system's malfunction. Now stranded in Haruhiko’s world, she is entirely dependent on him for her safe return. The only way to successfully reactivate the summoning circle and send her back is to resolve the very issue that caused the initial failure. With no other options available, Haruhiko is forced to confront his lifestyle and embark on a grueling journey to lose weight, turning an impossible magical predicament into a deeply personal challenge.