Five-member Tokio emerged in 1994 from Japan's now notorious boyband empire Johnny and Associates, which unravelled in 2023 following revelations about its late founder's decades-long sexual abuse of young boys.

Recent years have seen Tokio trimmed to a trio, and in a final death blow, it declared itself defunct Wednesday after it emerged that one of its members had engaged in unspecified misconduct.

Details surrounding the alleged misbehaviour of Taichi Kokubun, 50, are scarce, with official statements vaguely describing it as a "violation of compliance protocols".

A few mainstream media outlets in Japan, including Kyodo News, cited "behaviour that could be considered sexual harassment," quoting unnamed sources.

"We have decided it's no longer possible for Tokio to regain the trust and support of everyone", the group's statement, released Wednesday, said.

Aside from its music success, Tokio for long had another face: the ambassador for Japan's Fukushima region, hit in 2011 by a huge earthquake, tsunami and nuclear disaster.

Tokio's relationship with Fukushima predates the disaster, but afterwards it deepened even more with its members tapped to promote the region's reconstruction efforts and food safety.

Fukushima's prefectural government even has the "Tokio Department", a division tasked with collaborating with the musicians to communicate the region's attractiveness.

"For many years, Taichi Kokubun has aligned himself close to us and spread word" of Fukushima, its local government said in a statement, describing Tokio's disbandment as "extremely regrettable".

"Tokio's contributions to our prefecture's reconstruction are significant", it added.

Kokubun's fall in disgrace is just the latest in a recent series of bombshell scandals to rock Japan's showbiz industry.

Johnny & Associates, which has since changed its name, admitted in 2023 that its late founder Johnny Kitagawa had sexually assaulted teenage boys and young men for decades.

More recently, high-profile celebrities have found themselves entangled in sexual assault allegations, including J-pop megastar-turned-TV host Masahiro Nakai, who announced his retirement earlier this year.

The Nakai saga shed the spotlight on the toxic culture of young women being pressed into attending dinners and drinking parties with powerful industry figures.