Original Webtoon:
Ridibooks, Bomtoon, Lezhin

In the 90s, Leo Lowell was a test subject at a research institute that conducted unethical experiments on people. The experiments were painful, but he was able to endure them because of his friends and a doctor he liked, but he eventually became a discarded test subject by order from his superiors. Feeling betrayed by the doctor he trusted the most, Leo began hunting everyone in the research institute in order to get revenge...