Guiyeoni (Korean: 귀여니, born 1985) is the pen name of internet novelist Lee Yoon-sae (이윤세).
She first reached fame with her novel He Was Cool, which she serialized for 2 months since August 2001 in Daum's humor threads when she was a 2nd year in high school in Jecheon girl's high school.
[1] Subsequent works such as Romance of Their Own, spawned commercially successful films of the same name, as with another book, A Wolf's Attraction.
Since then, one of her other books, Do Re Mi Fa So La Ti Do, has become a film starring Jang Keun-suk.
Despite her commercial success, Guiyeoni has been criticized for her lack of literary perfection, overuse of emoticons,[2] and unrealistic setting in her works.