Sweetlove: Spoiled by My Childhood Sweetheart

He was aloof, reticent, and indifferent to women. Many girls expressed their liking for him, but he refused all with three sentences: "No way," "No need," "No possibility." Except for one person—her.
Since she moved in and lived with his family, he changed a lot. The used-to-be aloof guy not only helped her with her homework but also protected her all the time. He liked to tease her every day.
"Be good. I'll let you kiss me."
"I will only answer your questions."
"One wrong letter, one kiss."