Question: A singer who is a quarter Japanese, a quarter Chinese, and half German, is a member of a Japanese boy band that is managed by Johnny & Associates, and had an average age of what when they debuted?

Context articles: Sexy Zone
Marius Yo
Tatsuya Ueda
Kanjani Eight
Ryo Nishikido
Junichi Okada
KAT-TUN
SMAP
Hiroshi Nagano
Hey! Say! JUMP

Sexy Zone is a five-member Japanese boy band managed by Johnny & Associates, consisting of Shori Sato, Nakajima Kento, Marius Yo, Kikuchi Fuma and Sou Matsushima.When they debuted their group age average was 14.6.
 In 2013 they appeared in Kouhaku for the first time performing their hit song.
 Sexy Zone is the 5th group from Johnny & Associates to debut as special supporters for the "FIVB World Cup Volleyball" in 2011 after V6 (1995), Arashi (1999), NEWS (2003) and Hey!
 Say!
 JUMP (2007) from the same agency.
Marius Yo (マリウス 葉 , Yo Mariusu ) is a quarter Japanese, quarter Chinese and half German, singer, songwriter, actor, and "tarento" under Johnny & Associates and Pony Canyon.
 He is a member of the Japanese idol group Sexy Zone.
 Born in Heidelberg, Germany, his father is German and his mother is former Japanese/ Chinese Takarazuka Revue actress, Akira Yo.
Tatsuya Ueda (上田 竜也 , Ueda Tatsuya , born on October 4, 1983) , is a Japanese idol, singer, and actor from the Japanese idol group KAT-TUN.
 Born in Kanagawa in Japan, he joined the Japanese talent agency, Johnny & Associates in 1998.
 In March 2006 he debuted as a member of the Japanese boy band KAT-TUN and is under Johnny & Associates management.
 The group's name was an acronym based on the first letter of each member's family name until the departure of Jin Akanishi in 2010, and Koki Tanaka in 2013.
 Junnosuke Taguchi left the band a well in 2016.
 After Tanaka's and Taguchi's withdrawal, Ueda took the T's for TaTsuya.
 As of 2016, KAT-TUN stands for Kazuya KAmenashi, TaTsuya Ueda, and Yuichi Nakamaru.
 Ueda is very athletic, and his favorite hobbies include Boxing and running.
Kanjani Eight (関ジャニ∞（エイト） , Kanjani Eito , stylized as Kanjani∞) is a seven-member Japanese boy band from Japan's Kansai region.
 They are managed by the multimedia talent agency, Johnny & Associates, and signed to Imperial Records.
 The group was formed in 2002 and made their CD debut in 2004 as "Johnny's modern enka group", though after the year 2006, their sound and style has become a mix of pop and rock.
 Like the rest of the acts managed under Johnny & Associates, Kanjani Eight also perform in various other areas of the Japanese entertainment industry such as variety show hosting, television, movie, and stage acting, and radio talk show hosting.
Ryo Nishikido (錦戸 亮 , Nishikido Ryō , born November 3, 1984) is a Japanese idol, singer, actor and songwriter.
 He is a member of Japanese boy band Kanjani Eight and was also a member of Japanese male idol group News, both of which are under the management of Johnny & Associates.
Junichi Okada (岡田 准一 , Okada Jun'ichi , born November 18, 1980) is a member of Japanese boy band V6, which is under the management of Johnny & Associates.
 He joined Johnny & Associates at the age of 14.
KAT-TUN (カトゥーン , Katūn ) is a Japanese boy band formed under Johnny & Associates (Johnny's) in 2001.
 The group's name was originally an acronym based on the first letter of each member's family name: Kazuya Kamenashi, Jin Akanishi, Junnosuke Taguchi, Koki Tanaka, Tatsuya Ueda, and Yuichi Nakamaru.
 Their debut on March 22, 2006 was marked by a tripartite release of a CD single, album and music DVD on their exclusive record label J-One Records.
 Since then, all of their single, album and music DVD releases have debuted at number one on the "Oricon" music and DVD charts.
SMAP was a Japanese boy band, composed of Masahiro Nakai, Takuya Kimura, Goro Inagaki, Tsuyoshi Kusanagi, and Shingo Katori.
 The group was created in 1988 by music producer Johnny Kitagawa, founder of Johnny & Associates, originally as a six-piece with Katsuyuki Mori, until his departure from the band in 1996.
 After making their debut in 1991, the group took the Japanese entertainment industry by storm, becoming the most successful boy band in Japanese history and the best selling band in Asia, often referred to as a "national treasure" and a "fortune and property of the country" in Japan.
Hiroshi Nagano (長野 博 , Nagano Hiroshi ) is a pop singer, actor and member of V6, a Japanese boy band formed in 1995, under the management of Johnny & Associates and its half part, 20th Century.
 He is among the first who joined Johnny & Associates in 1986 at age of 14.
 He quit Johnny's Jr on 1990 to continue his studies and re-join on mid of 1992.
 He is famous and well known for his role in the popular Tokusatsu series, Ultraman Tiga as the series main lead, Daigo Madoka, the human form of Ultraman Tiga.
 In addition to appearing in the Ultraman Tiga TV series, he has also appeared in several spin-offs and feature films.
Hey!
 Say!
 JUMP is a nine-member Japanese all-male band under the Japanese talent agency, Johnny & Associates.
 The name Hey!
 Say!
 refers to the fact that all the members were born in the Heisei period, and JUMP is an acronym for Johnny's Ultra Music Power.
 They are also known as HSJ or just JUMP.
 Like agency seniors, Hikaru Genji and V6, the group is split into two sub-groups: Hey!
 Say!
 BEST (Boys Excellent Select Team) and Hey!
 Say!
 7 (not to be confused with the temporary group with the same name).
 The sub-groups consists of the five oldest members (BEST) and four youngest members (7) respectively.
 The average age of the group at the debut was 15.7, with the youngest member being 13 and the oldest 17.
 They have sold over 2,386,402 copies in Japan alone.
 The group debuted in 2007 with ten members, becoming the largest group to debut in Johnny's history.