| Birth Name: | Lee Yoon-sae |
| Birth Date: | 1985 |
| Birth Place: | Jecheon, South Korea |
| Nationality: | South Korean |
| Notable Works: | Do Re Mi Fa So La Ti Do |
Guiyeoni (ko|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. A movie of To My Boyfriend is also in planning stages. Despite her commercial success, Guiyeoni has been criticized for her lack of literary perfection, overuse of emoticons,[2] and unrealistic setting in her works. Besides the aforementioned novels, she has also written Africa, Five Stars, and written and illustrated a manhwa called Syndrome.
She married in 2018.[3]