Question: Kim Jae-joong, star of the series Triangle, is best know as a member of what pop group?

Context paragraphs:
Ideal (group): Ideal was an American R&B quartet from Houston, Texas, United States.  The group Ideal debuted in 1999 and is composed of brothers Maverick Cotton and Swab, their cousin PZ and high school friend J-Dante.  The group is best known for its hit songs "Get Gone" and "Whatever."  Ideal also had a 5th member who started with the Original Group in 1992, Charles Vienn II, who now goes by the stage name "EDWIN VICTORY".  He left the group in 1998 to pursue his own musical and entertainment interest.  He is best know for his creation of "The Baby Isaac Crew", a group of mascot characters who do positive and uplifting hip hop songs for kids.

Triangle (2014 TV series): Triangle () is a 2014 South Korean television series, headlined by Kim Jae-joong who plays Jang Dong-chul, the second of three brothers.  The other two brothers are played by Lee Beom-soo and Im Si-wan.  It aired on MBC from May 5 to July 29, 2014 on Mondays and Tuesdays at 22:00 for 26 episodes.  "Triangle" was directed by Yoo Cheol-yong and written by Choi Wan-kyu, who previously collaborated on the gambling dramas "All In" (2003) and "Swallow the Sun" (2009).

Spy (2015 TV series): Spy (, stylized as SPY) is a 2015 South Korean television series based on the Israeli drama "The Gordin Cell" but modified to depict North/South Korean relations.  A family drama with spy thriller elements, it starred Kim Jae-joong as a genius analyst working for the National Intelligence Service (NIS), while Bae Jong-ok played his mother, an ex-spy from North Korea.

No.X: No.X is the second studio album by South-Korean singer Kim Jae-joong, released on 12 February, 2016.  The songs represent various genres, including Brit pop, pop punk, post-grunge, blues, ballad and rock.  It sold over 85,000 copies, making it the 9th most successful album in the first half of 2016 in South Korea.  A music video for the title song, "Love You More" was released on 11 February.

The Very Best of Brother Beyond: The Very Best of Brother Beyond is a compilation from British boy band / pop group Brother Beyond, released in 2005, by EMI label, for its «Gold Series», containing all the quartet's greatest hits, as well as minor successes, including their very last single, that is the United States success called "The Girl I Used to Know" (never before included on any of their albums).  The record also contains five very hard to find 12" versions: "The Harder I Try", "Drive On", "Be My Twin", "Can You Keep a Secret?"  and "He Ain't No Competition".  The compilation, totally featuring 17 tracks, came out 15 years after Brother Beyond's last single.  Besides the above-mentioned five 12" versions, the collection also includes all 11 singles released by the group, between 1986 and 1991, plus 1 B-side (from 1986).  The album contains their only 2 Top 10 hits ("The Harder I Try" and "He Ain't No Competition", both produced by British producing team Stock, Aitken & Waterman); 1 Top 20 ("Be My Twin"); 1 Top 30 (the '89 remix to "Can You Keep a Secret?" ; the original version, which was here omitted, never got higher than the Top 60, instead); 1 Top 40 ("Drive On"); 2 Top 50 ("When Will I See You Again?"  and "The Girl I Used to Know"); 2 Top 60 ("Chain-Gang Smile", and their second album's title-track, "Trust"); and 1 Top 75 ("How Many Times").  The greatest hits collection also includes the very first single from the band, "I Should Have Lied", the only one which never succeeded in entering the UK Top 75.  As concerns the one B-side here proposed, this is the original version to the popular track called "Act for Love", previously contained, in its extended version only, in both CD editions of their first album, "Get Even".

Tommy Hoehn: Thomas Forbes "Tommy" Hoehn, Jr. (November 2, 1954June 24, 2010) was an American singer, songwriter, keyboard player, and guitarist.  Along with Jon Tiven, he led the Memphis power pop group Prix before embarking on a solo career.  He also provided backing vocals on Big Star's third album, "Third/Sister Lovers", and collaborated with Big Star members Alex Chilton and Chris Bell as well as Memphis power pop group The Scruffs.

Kim Jae-joong: Kim Jae-joong (Hangul: 김재중 ; Hanja: 金在中 ; born January 26, 1986), also known mononymously as Jaejoong, is a South Korean singer, songwriter, actor, director and designer.  He is best known as a member of the Korean pop group JYJ, and was one of the original members of boy band TVXQ.  Kim was also known by the stage names Hero Jaejoong (in South Korea), Jejung (ジェジュン) (in Japan), and 英雄在中 (영웅재중) (in China).  Kim is now using Kim Jae-joong (JYJ) for his activities.

Triangle (band): Triangle (トライアングル , Toraianguru ) was a Japanese pop group that formed and debuted in the late 1970s.  They released their first single, Triangle Love Letter in mid 1978 and their last single, Koi wa Tekkiri Ba-Bi-Bu-Be-Bo in 1980.  The group only released two albums, Triangle Love Letter and Sanjūsō / Triangle 2 in 1978 and 1979 respectively.  Sony Music Entertainment released Triangle Single Collection in 2008.

Manhole (TV series): Manhole () is a South Korean television series starring Kim Jae-joong, Uee, Baro, Jung Hye-sung.  It aired on KBS2, from August 9 to September 28, 2017 on Wednesdays and Thursdays at 22:00 (KST) for 16 episodes.

Hitomi Yoshizawa: Hitomi Yoshizawa (吉澤 ひとみ , Yoshizawa Hitomi , born April 12, 1985 in Miyoshi, Saitama, Japan) is a former leader of the idol pop group Morning Musume, idol, actress, model and current member of the pop duo Hangry & Angry as Hangry.  She is the current leader of the Hello!  Project futsal team Gatas Brilhantes H.P. and the idol group derived from its lineup, Ongaku Gatas, and is also currently a member of Japanese pop group Dream Morning Musume.

Supporting paragraphs: Triangle (2014 TV series) Kim Jae-joong
Answer: JYJ