The Dungeon of Black Company Series by Youhei Yasumura

Kinji had it made -- a swank apartment, a real estate empire, and enough cash to lounge around living the good life. After a freak magical accident, he washes up in another world, all but enslaved to a crooked corporation. In a fantastical land where money is everything, there's only one way for an Earthling to get ahead: make your fortune, by any means necessary! Dragons, goblins, and the occasional dubious potion won't stop Kinji's quest for the world's biggest bank account... moreKinji had it made -- a swank apartment, a real estate empire, and enough cash to lounge around living the good life. After a freak magical accident, he washes up in another world, all but enslaved to a crooked corporation. In a fantastical land where money is everything, there's only one way for an Earthling to get ahead: make your fortune, by any means necessary! Dragons, goblins, and the occasional dubious potion won't stop Kinji's quest for the world's biggest bank account. The Black Company is open for business! less

Kinji's got the worst luck in the universe. Right after he hit the big time on Earth, he got transported to another world. Forced to toil for corporate overlords in the depths of a perilous dungeon, there's no scheme he won't try to strike it rich. After a 'promotion' to the most dangerous unit in the company, Kinji reluctantly teams up with Shia, a bona fide Hero and a true believer in the company cause... moreKinji's got the worst luck in the universe. Right after he hit the big time on Earth, he got transported to another world. Forced to toil for corporate overlords in the depths of a perilous dungeon, there's no scheme he won't try to strike it rich. After a 'promotion' to the most dangerous unit in the company, Kinji reluctantly teams up with Shia, a bona fide Hero and a true believer in the company cause. With the help of a hero, a lizardman, and a hungry dragon, he just might be able to survive long enough to make his fortune! less

What's worse than getting thrown through a portal to a strange, dangerous world? Getting thrown through another portal to an even more dangerous world! Just when Kinji thought he'd defeated the boss of the dungeon, he finds himself in unfamiliar territory, surrounded by ruins and strange technology. What's worse, the locals are calling him their messiah. One thing's for sure -- they didn't count on a savior as crooked as Kinji. He'll try any scheme, no matter how crazy, to make it home alive!

NO WAY UP BUT DOWNKinji’s got a new scheme to get one over on his corporate masters–he’s going to claim the mine all for himself. The race is on: the world’s biggest company against the world’s biggest scoundrel, with unimaginable wealth and power as the ultimate prize!

The key to ultimate power is waiting at the bottom of the dungeon, and Ninomiya Kinji is in a race with a crooked megacorporation to get his hands on it. But there's one small problem -- he's totally broke. An unlikely get-rich-quick scheme might provide the answer, as Kinji joins forces with destitute shopkeeper Cindy, and soon, every adventurer in the world will be clamoring for... magic energy drinks?!