Koshino Junko (コシノジュンコ) is a Japanese fashion designer and honorary lifetime member of BiS.
Koshino graduated from the Bunka Fashion College in 1961, winning the 7th SO-EN award. She opened her first boutique, COLLETTE, in Tokyo in 1969. In 1980, she launched her first menswear line, Mr Junko, and launched a home furnishing line the following year. In 1992 she designed the uniforms for Japan's Olympic volleyball team.
On October 28th, 2013, Koshino Junko was announced as a member of BiS after they had previously teased that a "JK" would be joining the group (JK usually known as a slang term for high school girls). For the next week, BiS would appear alongside her to promote her new handbag line at HOT DENPO FESTIVAL, and releasing the single Koisuru Denpo JAPAN.
After promotion activities ended on November 5th, Koshino stopped making appearances with BiS, however, was made an "honorary life member" of the group.
She comes from a family of prestigious fashion designers; her mother was Koshino Ayako, and her sisters are Koshino Hiroko and Michiko.
She is married with one son.
- She is the oldest BiS member of all time (being 51 years older than the second-oldest member, First Summer Uika), as well as one of the oldest idols to ever debut (joining BiS at the age of 74).