After being summoned to another world as the 68th hero, Setsuna Sugimoto is abandoned by that same world due to his sickly constitution. But when he meets Kyle, a millennia-old former hero like him, Setsuna is given a third chance at life—inheriting Kyle's knowledge, power, and even life force. Now able to travel the world as an adventurer, Setsuna will encounter people from all walks of life, with each meeting bound to leave a lasting mark on himself and the world. And so begins a journey full of firsts...