In 2015, Yook joined King of Mask Singer, competing under the alias Tired Bumblebee, and received good feedback for his performance. He received the "New Star award" for his performance in The Village: Achiara's Secret, and won "Best Couple award" with Kim So-hyun for Who Are You: School 2015.
AMBIGUOUS BTOB LYRICS SERIES
Yook then starred in the horror mystery series The Village: Achiara's Secret alongside Moon Geun-young in 2015. After the series ended, he experienced a rise in popularity and landed several endorsement deals. He also released an OST for the show, "Love Song" with Park Hye-soo. Yook achieved his breakthrough when he landed a leading role in the teen drama Who Are You: School 2015, alongside Kim So-hyun and Nam Joo-hyuk. 2015–2017: Acting and rise in popularity He then joined the reality-variety program Real Men from 2014–2015.
AMBIGUOUS BTOB LYRICS PLUS
The same year, he received his first main acting role in Plus Nine Boys, playing a 19-year old Judo athlete. The group then releases two singles: "Stress Come On" and "Ojingeo Doenjang" (Korean: 오징어 된장). He also participated in the program Hitmaker season 1, presented by South Korean producer duo Jeong Hyeong-don and Defconn and became part of the program's project unit group, Big Byung, together with Got7's Jackson and VIXX members, N and Hyuk. In July 2014, Yook was cast as a presenter for the program, A Song For You alongside Kangin of Super Junior and Amber of f(x). In 2014, Yook appeared in the television series Reply 1994 as Sungjoon/Ssukssuk, Na-jung's little brother. In the same year, Sungjae and BTOB made a cameo appearance in hit drama " The Heirs" episode 4 as themselves, an idol group band BTOB.
He, with BTOB's Lee Minhyuk, Lee Changsub, Im Hyunsik and Beast's Yong Jun-hyung were featured in the drama OST Part 1 titled "Days Gone By", OST Part 2 "After Time Passes", and OST Part 7 "First Love". He appeared in 4 episodes in total, episodes 2, 6, 9, and 12. Sungjae acted as Arnold, a member of boy idol group 'Men In Black'. In 2013, Yook Sungjae started his first ever acting debut in drama Monstar (TV series) as part of the supporting cast alongside his bandmates Lee Min-hyuk, Lee Chang-sub and Im Hyun-sik. On March 23, 2012, Yook co-host SBS MTV's music program The Show alongside bandmate Lee Min-hyuk. Yook made his debut as a vocalist of BtoB with "Insane" and "Imagine" on March 21, 2012. 2012–2014: Debut with BtoB and solo activities Yook entered the JYP 6th Audition Final Round before joining his current agency, Cube Entertainment. On March 6, 2011, Yook also participated in the stage performance of "2011 CUBE Stars Party" with bandmate Seo Eunkwang, Im Hyun-sik, Jung Il-hoon, and supposed to be member Lee Min-woo. On August 10, 2010, he participated in the stage performance of "2010 Cube Stars Party". He then attended Dongshin University, majoring in Practical Music. He completed his high school education at Hanlim Multi Art School, graduating in 2014. He briefly studied for a month in England and the Philippines, respectively. His grandfather was the first to introduce red carp in South Korea, while his grandmother operated a fishing farm in Paju. His father is the CEO of an IT corporation that deals with semiconductors. Yook was born on May 2, 1995, in Yongin, Gyeonggi Province. 2.4 2018–present: 3x2=6, Yook O'Clock and Mystic Pop-up Bar.2.3 2015–2017: Acting and rise in popularity.
2.2 2012–2014: Debut with BtoB and solo activities.