Matthew has found himself in an unusual arrangement in the gritty dungeon city of Gray Neighbor. By day, he's known as a worthless freeloader, content to squander the money his keeper, the capable princess knight Arwin, provides him. Arwin, the celebrated Crimson Princess Knight, leads her party of adventurers into the dungeon at the heart of the city in search of a fabled treasure that could restore her fallen kingdom. The townsfolk loathe Matthew as a coward who wastes her earnings on drink, women and gambling. Yet nobody, Arwin included, knows what he can really do: in secret he is a merciless guardian who will go to any length for her sake. The result is a fantasy action comedy with a streak of romance.