Kamishita Seiji suddenly gets summoned to another world and starts helping God with creating a new world based on RPG games.
After teaching the God everything he knows, he gets told that he cannot go back to his former world, so the God offers to give him development cheats, but Seiji thinks it would feel strange to live his life in such a way.
As a result, Seiji chooses to reincarnate with a different cheat that lets him get stronger depending on how much effort he spends: He needs ten times more experience to level up than other people do, but in exchange, he can enter dungeons to train as much as he wants without worrying about time.
Kamishita Seiji reincarnates as the eldest son of a poor family as Seiji Slowdish, but he is able to use his leftover experience points after leveling up to purchase magic, skills or even goods from Japan.
He receives a book called Parallel World Online Shopping.
Thus begins his reincarnation story of great effort and determination to level up and use leftover experience points for online shopping as he still cannot decide whether he’s suffering or having fun.