High school student Asahi Ikusaba, an RPG otaku who has always dreamed of adventuring in another world, gets his wish when he is rendered comatose after getting hit by a car while saving a child. Finding himself in a fantasy world, he pursues his desire to become an adventurer. However, he is outmatched by high-level monsters he stumbles across on his very first quest. Suddenly, his overprotective older sister Maya appears and saves his life. Partnering up with him, the two begin to make their way in this new world, even though Asahi comes to fear his sister's overbearing affection for him more than the various dangers this world has to offer.