Sung Deok-mi (Park Min-young) is a talented chief curator of Cheum Museum of Art, who also happens to have a secret: she is a fanatic fangirl of White Ocean's Cha Shi-an (Jung Jae-won). In addition, she is also the fansite manager of the famous "The Road to Sian" (Korean: 시안은 나의 길; RR: Sianeun Naui Gil; lit. Sian is My Way), the abbreviation of which (Korean: 시나길; RR: SiNaGil) she uses as her screen name. Ryan Gold (Kim Jae-wook) is a standoffish artist who develops Stendhal syndrome, eventually retiring as an artist. After the current boss, Uhm So-hye (Kim Sun-young), is investigated for embezzlement, Ryan Gold becomes the new Art Director of Cheum Museum of Art.
After unfounded rumors break out claiming Deok-mi and Shi-an are dating, Ryan suggests he and Deok-mi pretend to date to ward off Shi-an's fans who threaten to harm her. However, Kim Hyo-jin (Kim Bo-ra), Um So-hye’s spoiled daughter who, unknown to her mother (who would strongly disapprove), is another fansite manager of Cha Shi-an under the pseudonym Sindy, manages to land a job as an intern in the museum seeking to prove Ryan and Deok-mi are a fake couple, leaving them both no choice but to continue the act even at work. Eventually, they fall in love.
The chief curator at Cheum Museum of Art who often does not get credit for the work she does under Director Uhm, an incompetent socialite. She runs a fan website called "The Road to Sian" which she intends on keeping secret. She later falls in love with Ryan.
The standoffish new art director of Cheum Museum of Art who is very strict and he is allergic to caffeine. After seeing Lee Sol's painting, he develops Stendhal syndrome which prohibits him from painting, eventually leading to his retirement. He is also famous in New York for his perspective on new artists. He eventually falls in love with Deok-mi.
An Olympic silver medalist in judo who opens his own gym and becomes an instructor. After his single mother abandoned him in the hospital, Deok-mi's mother took him in and raised him with Deok-mi as family. After learning about Deok-mi's fake relationship with Ryan, he realizes he is in love with her.
Deok-mi's best friend who is the owner of CocoMoco café which Deok-mi, Ryan, and Eun-gi frequents. Like Deok-mi, she is also a fangirl of Cha Shi-an who often voices her sadness she can no longer be a full-time fan after becoming a mother. She helps with the creation of Ryan and Deok-mi's fake relationship. After seeing her employee, Joo-hyuk, at a concert, she becomes a fan and makes and runs a fan site for him.
Deok-mi's mother who is a knitting-obsessed woman who is often portrayed as a head of the household. She urges Deok-mi to give up being a fangirl, citing it would be difficult for her date since men would find her hobby off-putting. Not knowing Ryan and Deok-mi's relationship is fake, she becomes ecstatic and treats Ryan as her future son-in-law, inviting him for dinner and giving him side-dishes.
A chief editor of an art magazine and mother of Nam Eun-gi. After having personal troubles, she lets Young-sook care for her son since he was an infant. Young-sook and Se-yeon becomes friends and have accepted that they are both the mother of Eun-gi. Although she has a good relationship with her son, he often calls her as "Editor Nam" and Young-sook as "Mom", which she doesn't seem to mind.
A visual art director from New York who is in love with Ryan, her friend of ten years. She follows Ryan and moves to South Korea. She works at Cheum Museum of Art in collaboration with Cha Shi-an for his upcoming album and art exhibition. Feeling dejected learning about Ryan and Deok-mi's relationship, she becomes happy after Eun-gi tells her their relationship is fake.
An idol and the most popular member of the boy group, White Ocean. He adores the fansite "The Road to Sian", stating that it is the only fansite whose owner seems to understand him. He is a fan of artist Lee Sol and plans on collecting all of her nine paintings. He grew close to Ryan Gold after learning that they were neighbors.
A wealthy and eccentric former art director of Cheum Museum of Art who resigned after her investigation of embezzlement and slush funds. Despite resigning, she plans on taking back her position after the investigation is completed. She remains a powerful authority in the museum after becoming the head director of TK Cultural Foundation, which funds the museum. She uses her connections to get her daughter, Sindy, a job in Cheum Museum of Art as an intern.
An investigative intern in Cheum Museum of Art and the daughter of the former art director, Uhm So-hye. She is a fan of Cha Shi-an and runs a fansite called "Sindy" where she calls out Deok-mi as Shi-an's girlfriend. After an article comes out reporting that Ryan and Deok-mi are dating. Hyo-jin uses her mother's connections to get a job in Cheum Museum of Art. She makes another site called "CUPATCH" where she investigates the validity of Ryan and Deok-mi's relationship. Eventually, it is shown how she becomes a part of the Cheum Museum family through her determination, creativity and hard work.