men, as they represent their "eternal longing" and nostalgia for high school, while only gaining popularity with women in the 2010s through anime. Retirement Idols are typically expected to change careers after aging out of the industry, with female idols typically changing careers at age 25 and male idols at ages 30–45. Idols who leave a group are often given a farewell concert known as . The term originated from the idol group Onyanko Club, as the group's youthful concept drew similarities to an after-school club, and the fact that Miharu Nakajima's final single before retirement was released around graduation season in Japan. Prior to the 1980s, the terms "retirement" and "disbandment" were used. "Graduation" saw usage again in the 1990s during the revival of idol groups when Tsunku, who produced the group Morning Musume, used the term as a euphemism regarding one of the members leaving the group. An idol having a "graduation" ceremony is seen more favorably than terminating a contract or voluntarily withdrawing, as the latter two terms are negatively connoted with scandals. Sub-category markets The diversity of Japan's idol industry has created several sub-category markets, each with a specific concept appealing to certain audiences. : AV (adult video) idols generally refer to pornographic actresses and models, with the industry first emerging in the 1980s. : Bandols are idol groups that play instruments and perform as bands. The term first emerged in the 2000s as a shortening of the phrase, , which was used to describe the marketing concept of the band Zone. : Gravure idols are models who pose in provocative swimsuit and lingerie photographs in magazines and photo books marketed towards men, similar to pin-up models. In the 1970s, Agnes Lum, whose rose to fame in Japan, is considered the first gravure idol despite the term not existing at the time. Other notable swimsuit models were , , and Fumie Hosokawa. After Akiko Hinagata became a rising star in 1995, the term "gravure idol" was coined to describe her. In the 2000s, there was a significant growth in the gravure idol industry, with many women of different body types modeling. This led to sub-category markets in the gravure idol industry to describe their aesthetic and body types, which included , , , , and . The gravure idol industry faced a decline in 2010 due to the popularity of AKB48, as some of their members