Aju Jogeum Monan Somsatang
"How can someone not fall in love?"
After being kidnapped, 9-year-old Yo-Han is rescued with the help of Seong-Jin, a highschool student passing by. As a result, their relationship continued as Yo-Han's family sponsored Seong-Jin. As time passed, Yo-Han and Seong-Jin became lovers.
Yohan tries his best to become a great, competent, handsome, friendly, and mature lover who's not an embarassment to Seong-Jin. But sometimes he reaches his limit...
(Source: Ridibooks, translated)