If you're looking for manga similar to Introduction to the Theory of Love, you might like these titles.
“Jun” was adopted as the second son of the Ato Group on the condition that he protects the home with the memories of his father. But to keep his house completely, he has to become the president of the Ato group! To become the president, he checks in with "Ji-hoo" and "Min-hoo" who are brothers but not brothers, but soon finds himself falling for each other.
On the first day of university, Haebin, who had never been rejected before due to his gorgeous/handsome appearance, met Shiyul, who was prickly from their first meeting, and began to get butterflies. At the end of a long while of clinginess, Haebin finally entered Shiyul’s room! After watching a gay porno his friend sent as a joke, he got swept away in the atmosphere and kissed Shiyul, who reacted with fear and surprise, rejected him, and even hid while crying. Will Haebin be able to overcome Shiyul’s trauma and kiss him in the end?
'Im Rok' has the nickname 'Lucky Deer', always with good luck. As usual, he won an event and went on a trip with his friends. He is invited to the island of Noah, a handsome and kind man. Luxurious islands and homes, they can't stop at Noah's hospitality. However, oddly enough, each of his friends disappeared, and to make matters worse, Imrok was freaking out underground.
I didn't think this one sided love would come true. As it is, I wish we could just remain friends. Dokyung wouldn't like it if he knew how I feel about him, so that's the only way. However, Yoon Jae, who has been in one sided love with Do-kyung, is shaken by the appearance of Kyung-won who...