In 1982, Higashiyama joined the group in place of Matsubara and became Shonentai, working as a backup dancer for Toshihiko Tahara and Masahiko Kondō.

[15] Higashiyama was a stoic, hardworking person who watched Michael Jackson music videos after school in his dormitory and worked on his muscle training every day.

[17] They appeared on music programs such as Yoru no Hit Studio (Fuji Television) even before their record debut, won a gold medal and a choreography award at Music Festival of Hawaii in November 1982, and in 1983, two TV series After School with a Sizzling Heart (Fuji Television) starring the three of them were aired, and in 1984 In April, they held their first solo concert in Tokyo.

[18] They would see and learn from musicals on Broadway theatres and even take dance lessons in the U.S..[18][12] They were also prepared to make their U.S. debut and recorded an English-language song produced by Michael Sembello, but it did not come to fruition because they became busy with work in Japan.

[16] [Note 2] On New Year's Eve 1984, Nishikiori made a direct appeal to Mary Yasuko Fujishima, Kitagawa's elder sister, who was involved in the management of Johnny's, at a company year-end party, to let them make their debut, even if it was on a flexi disc.

[16] The following year, they won Japan Record Award for Best New Artist in 1986, and the happening that Yūzō Kayama, captain of the white team, introduced them as Kamen Rider at the 37th Kōhaku Uta Gassen is well known.

[18] In TV singing shows of the time, singers usually sang in front of musicians prepared by the TV station, but since Japan was in Japanese asset price bubble at the time, Shonentai sometimes went all the way to the U.S. to sing live on air in Las Vegas or in front of used car dealerships with many American cars.

[30] As for their individual activities, as an actor, Higashiyama performed a wide range of roles, from jidaigeki, detective stories to comedies.

[35] Johnny's official website stated, "Shonentai, as an analogy, is a group that has steadily accumulated enough achievements over the past 35 years to deserve to be inducted into the Hall of Fame.

Although we have no plans to be active as a group in the future, we have decided to create an environment in which we can continue to be a beacon for our junior members at the Johnny's without any change,[35] We thank them both for their past accomplishments and send them on their new journeys."

[39] Nishikiori explained the reason, "After Kitagawa passed away, there was farewell ceremony for concerned persons only, attended by all of Johnny's talents.

"[38] Uekusa said that the reason why he left Johnny's was because "as we get older, our way of thinking changes, and we decided to do what each of us wants to do independently,"[40] and he described relationship with Higashiyama and Nishikiori as fatal bond, and explained he would continue to talk to both of them about anything, and would remain open.