Doomsday Grocery Store

Somewhere within the high walls where humans live, there is such an inconspicuous shop. As long as the materials are met, anything can be made. "I like the golden guide wheel gun very much. What materials are needed?" "The bones of a 4A-level iron-blooded rhinoceros and an S-level golden bird will do." "Hey, I want to install the best engine for my car. Do you have any recommendations?" "You go kill the Underworld Train first, and then we can talk." "Boss, I really want the Magic Wing Helicopter!!" "Looking at your shriveled appearance, can you kill the 3S-level Twilight of the Gods?" The shop owner looks lazy and has a cigarette hanging from the corner of his mouth all year round. Secretly, but persistently exploring the reasons for all this.