Eternal Thief - Chapter 14: Soul Cultivator!

Cho Kang-hyuk, the owner of a large fitness center, woke up to find himself a young disciple at Shaolin Temple.

A decade ago, the first dungeon gates appeared, but some vanished before they were ever conquered. The MC, a low-rank hunter, awakens the Lost Gate System, granting him access to these forgotten dungeons where legendary monsters and artifacts are trapped. Each completed lost gate grants him absurd power, but also reveals terrifying truths—these dungeons are prisons for ancient beings who want revenge.

What would you do if you were transported to an academy where becoming immortal was possible? Where magic spells and swordsmanship were your courses and fighting zombies and wars were your exams? Dawn Academy was no ordinary learning institution and Xiao Lin was about to find out how mysterious and exciting this magical academy really was.

Kyle woke up in a land of fantasy and magitech. The usual 'I died and woke up' bullshit, skip all that.

Except he used to be a crime lord, and society here is missing that extra kick.