Hanjoo Yeo, the MC, has been an outsider his whole life. People and family avoid him and find him weird. The only person that considered him family was his aunt who died when he was young. Hanjoo in dispair about his loneliness, goes to a rumored cursed tree that can fulfill wishes. Hanjoo asks for someone to stays with him forever and asks for a family.
Hanjoo has been hopelessly in love with the most popular guy in college, Chanyoung Choi (1st ML). After confessing his feelings, they become fuckbuddies but Hanjoo finds himself miserable for this unrequited love and is unable to end the relationship. Chanyoung doesn't want to date him and just wants the MC's body. But He is the only one in the school that doesn't find Hanjoo weird.
Hanjoo's father remarries and introduces Jihyun Yoo, his step-brother, who is extremely overworldy handsome (2nd ML). Jihyun goes to the same college as Hanjoo and the people around them, including Chanyoung doesn't find him attractive and pereceive him differently than Hanjoo. As if Jihyun changes his appeareance.
The step bro Jihyun acts misteriously, like not familiarized with modern korean society, tries to separate Hanjoo from Chanyoung and becomes kind of clingy and manipulative with Hanjoo.
Chanyoung doesn't trust Jihyun and suspects he is something else but can't describe it. Also he is starting to get a bit jealous about the relationship between the MC and the step-bro, so he tries convice Hanjoo to stay by his side. Eventually their classmates see how attractive is Jihyun and Hanjoo and they try to approached them and invite them to drink.
After the party, Jihyun confesses to Hanjoo that he is the not human and he met him in the tree. So he was born from his desire. Hanjoo remembers his wishes and has sex with this supernatural being. End of season 1
So far it is unclear what is Jihyun. But we know he has lived for centuries and he lived with others like him in a village.
Can someone please summarize this manhwa for me if ever you have time (￣ε(#￣)Σ