Dimensional Storekeeper

In countless worlds, mysterious doors appear, leading to an ordinary-looking convenience store. That is, until you see who’s inside. An immortal cultivator ponders over instant noodles flavor, an ancient demon sips a cola, and a primordial beast carefully holds a bag of potato chips. Beings who could shake the heavens stand quietly in line, waiting their turn. At the counter, a young man scans their purchases. No one knows where he came from, but all understand one thing. In this store, rules must be followed. Welcome to the Dimensional Convenience Store, where even the greatest existences must check the price before they buy. — Description from novelcodex.org