Ice Age Apocalypse: I Hoard Billions of Supplies - Chapter 613: Tidal Tiger

A 30-year-old NEET is reincarnated into the body of an otaku that choked to death on instant noodles. As he comes to grips with his new life, he realizes that this world is subtly different from Earth. The denizens of this world are far better looking, and this new world also possesses futuristic technology as well as mysterious Yin Yang masters!

I was reincarnated into another world, and I’ve brought the Horadric Cube from Diablo II with me.
Being a knight is cool and all, but being a wizard is pretty neat as well.
So, which one will it be?

- Description from Novelupdates

To survive, the unfortunate Gong Qiying, who became the lord of the Sein Dungeon, had to make his dungeon extremely “hellish”:Doors that “cannot be opened from this side”,treasure chests “triggering teleport traps”,a three hundred and sixty-five mile journey from the starting point to the BOSS room with no place to rest,monster knights with great bows on either side of a narrow bridge,and sinister ambushes around corners.There's also unavoidable visits to poisonous pits and hidden paths...Additionally, well-known fighters like Isshin Ashina, the Furnace Knight, Rajang, and the Scourge Legion bring unexpected surprises!Various unique rewards such as the Flaming Sword, Murky Hand Scythe, Rapid Slash Longsword, Sacred Oath, and Flame Empowerment will make you too happy to contain your joy!Gong Qiying: The most important thing in my dungeon is to ensure adventurers have fun!

Ajax used to coast through life before his parents died, after that he focused hard to try get his life back on track but that wasn't really happening and it all ended the day he got mugged. Given a second chance at life he now looks to become someone who matters and is willing to work hard from the beginning to make that happen.