Vivarium

Yoo Heesung is…not a nice person, to say the least. Arrogant, selfish, and criminally lacking in loyalty. So when he decides to steal from his childhood friend, their years of history don’t really weigh upon his mind. Until he wakes up, head pounding, tied to the bed of a dingy room?! Choi Jaeyeon knows just how awful Heesung can be, and is determined to teach him a lesson he will never forget.
(Source: Lezhin US)
Note: Chapter count includes an epilogue, 6 side story chapters, and a Christmas extra.