Urban Star Times Grocery Store

Travel through a parallel world and obtain a super-smart phone from the interstellar era, which can be used to trade with humans billions of years later. A bottle of drunk mineral water is worth two million Galaxy coins. A secret book bought on the roadside is worth 20 billion Galaxy coins. A fantasy novel, in exchange for a black hole-level science fiction weapon. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.