Question:  Guardian: The Lonely and Great God starred what BtoB boy group member?

Context paragraphs:
Im Hyun-sik (singer): Im Hyun-sik (Hangul: 임현식; born March 7, 1992), simply known as Hyunsik, is a South Korean singer-songwriter.  He is best known as a member of South Korean boy group BtoB.

Lee Min-hyuk: Lee Min-hyuk (; born November 29, 1990), commonly known as Minhyuk or Heota, is a South Korean singer, rapper, songwriter and actor.  He is a member of the South Korean boy group BtoB.  He received multiple supporting roles in television series such as "A New Leaf" and "Sweet, Savage Family".

L.U.V (BtoB song): L.U.V is the fifth Japanese single of the South Korean boy group, BTOB.  It was released on June 15, 2016 by Kiss Entertainment.  The single album also peaked at #1 on the Daily and Weekly Oricon Singles Chart, making it BTOB's first Japanese single to reach number 1.  It sold more than 62,000 copies on its first day, and 77,000 copies on its first week.  The song also reached number-one on the Billboard Japan Hot 100.

Remember That (EP): Remember That is the eighth EP of the South Korean boy group, BTOB.  It was released on March 28, 2016.  It is also the third installment to the BTOB's ballad trilogy, promoting the lead single "Remember That".  BTOB's own members participated in the production of all the songs in this album.

Guardian: The Lonely and Great God: Guardian: The Lonely and Great God (), known internationally as simply Goblin, is a South Korean television series starring Gong Yoo, Kim Go-eun, Lee Dong-wook, Yoo In-na, and Yook Sung-jae.  It aired on cable network tvN every Friday and Saturday at 20:00 starting December 2, 2016 until January 21, 2017.

Born to Beat: Born to Beat (BTOB) is an EP by South Korean boy group BtoB under United Cube Entertainment.

Yook Sung-jae: Yook Sung-jae (; born (1995--) 2, 1995 ) is a South Korean singer, actor and host.  He is a member of the boy group BtoB and its sub-group, BtoB Blue.  Aside from his group's activities, Yook is known for acting in television dramas, "" (2015), "" (2015) and "" (2016).

The Great God Pan: The Great God Pan is a novella by Welsh writer Arthur Machen.  A version of the story was published in the magazine "The Whirlwind" in 1890, and Machen revised and extended it for its book publication (together with another story, "The Inmost Light") in 1894.  On publication it was widely denounced by the press as degenerate and horrific because of its decadent style and sexual content, although it has since garnered a reputation as a classic of horror.  Machen’s story was only one of many at the time to focus on the Greek God Pan as a useful symbol for the power of nature and paganism.  The title was possibly inspired by the poem "A Musical Instrument" published in 1862 by Elizabeth Barrett Browning, in which the first line of every stanza ends "... the great god Pan."

I Mean: I Mean is the seventh EP of the South Korean boy group BTOB.  It was released on October 12, 2015 with the lead single ""Way Back Home"".  The EP contains 6 tracks.  It features the group's strong vocal skills.  This also leads to BTOB's growing success as they achieved their first music broadcast trophy through this album.

Jung Il-hoon: Jung Il-hoon (; born October 4, 1994), simply known as Ilhoon, is a South Korean rapper, songwriter, record producer, and actor.  He is the main rapper of the South Korean boy group BtoB.  He is well known for his multiple song featurings with artists such as Hyuna and G.NA and as an assistant MC in the variety show "Weekly Idol".  Ilhoon made his acting debut as he starred in the drama "Webtoon Hero: Tundra Show" in 2015.  He was also known for inventing and popularizing the gestures for "Gwiyomi Player".

Supporting paragraphs: Guardian: The Lonely and Great God Yook Sung-jae
Answer: Yook Sung-jae