Summary

"My Little Sister Turned into the Ultimate Holy Sword!? A Sibling Power-Comedy Adventure!" One ordinary day, high schooler Yuuya Amamiya finds himself whisked away to another world. But he’s not alone—his ultra-brother-loving little sister, Kokoa, a precocious 3rd grader, is along for the ride! As if being thrust into the role of the chosen hero tasked with saving the world from the Demon King wasn’t enough, Yuuya quickly discovers an unexpected twist: Kokoa has transformed into the strongest holy sword! With a weapon that’s not only sentient but also overwhelmingly overprotective of her big brother, Yuuya’s journey is anything but ordinary. Though he’s the "hero" in name, it’s clear that Kokoa’s power far surpasses his own—turning their mission into a chaotic, laugh-out-loud adventure as Kokoa effortlessly handles enemies that should terrify even the mightiest of warriors. As the siblings bicker, bond, and battle their way through this fantastical world, Yuuya must come to terms with his overpowered, ultra-adorable sister constantly stealing the spotlight (and maybe saving his life more often than not). Will they manage to vanquish the Demon King? Or will Kokoa's obsession with her "oniichan" prove to be the biggest obstacle of all? A heartwarming and hilarious story of sibling love, epic battles, and unstoppable power!