A story of an emergency room doctor who died from overwork and was transported to another world. The sails of the Great Voyage have already been raised. The steam engine has yet to roar. The glory of the Lord of Light shines upon the continent, and across the sea, on the islands, the churches of the gods and magicians support the monarchy together. Dwarves walk freely in the kingdom's cities, werewolves, vampires, elves, dragons... their legends have never faded. And Wu Zhou, the emergency room doctor who died from overwork, was transported to this era, into the body of the city guard boy, Gret. Teammate: Not good! The captain is seriously injured! His intestines are coming out! Gret: Help me up, I can still sew! Gret: Close the abdomen. Teammate: ...What? Gret: ...Give me a minor injury treatment...