The Heavens Pawnshop

Otherworldly Merchant Who Only Cares About Money, Minds His Own Business, and Has No Female Lead

Something like The Strongest Shopkeeper in History.

Opening a Shop with a System: A Mysterious Pawnshop Where Anything Can Be Traded

A pawnshop or store where people can trade their lifespan. Ideally, it has a System or was inherited as a mysterious shop.

The Protagonist Owns a Shop Outside the Six Realms Where Anything Can Be Traded

This shop lies beyond the six realms, and every kind of being in the world can come trade there. You can exchange things for money, power, time, and more. As long as you can pay the price, you can get whatever you want. It's similar to "Night Watchman".

Looking for Stories Like a Trading Mall Across the Myriad Worlds

Trading Mall, City of the Heavens.

A Merchant Cares Only About Money, Not People: Utterly Profit-Driven and Never Helps Others for Nothing

The Protagonist Runs a Pawnshop That Takes Anything as Collateral