Buying Goods from Another World, I Became Famous by Opening a Grocery Store

[Female protagonist + stall setting + apocalypse + time travel + system] The pace is a bit slow, 3 worlds A 14-year-old girl met a mysterious old man who gave her a stone. This ordinary stone changed the trajectory of the girl's life. Let her meet a good friend who will stay with her for a lifetime. They travel through time and space together and start new adventures in each world During the trip, the girl discovered the truth about the world, which was not peaceful. Facing the coming doomsday, what choice will the girl make?