Yuryeong Sagwa

Seo Won, the sole heir to the Kangsan Group and an S-class Esper. After being pushed to the brink of death by a certain accident, he undergoes a heart transplant from an S-class Esper in order to survive. However, that heart already bore the imprint of another Guide. To survive, he must find the owner of that imprint and bind them to his side. Meanwhile, Cha Han-Gyeom, an unregistered Guide who escaped after being used as a test subject at the Association’s unofficial research facility, has been living without even the will to live ever since losing his Marked One five years ago. Then, one day, a man engulfed in a dark aura on the verge of losing control appears before Han-Gyeom. “Cha Han-Gyeom.” A man who calls out a name Han-Gyeom has never heard before with such natural ease. And there, on that man’s heart, was clearly Han-Gyeom’s own mark. Seo Won, who needs Han-Gyeom to survive, and Han-Gyeom, who has already given up on life. The contract they entered into to save each other gradually transforms into obsession, possessiveness, and love... (Source: Ridibooks, translated)