In 1985 she also travelled to Switzerland to record a music film for her singles and songs so far, it was called "Yukiko in Swiss", if you have the chance to watch it I recommend it,
it's amazingly cute, you can probably find the whole thing on Youtube.
In 1986 she hit the number one mark with her single "Kuchibiru Network" which was written by Matsuda Seiko, and was also the advertising song for Kanebo Cosmetic's spring campaign
(this is a rather prestigious thing for an idol to do, as Matsuda Seiko, Koizumi Kyouko, and Kawai Naoko have also advertised for it.) Her success with Kuchibiru Network,
which was her 8th single gained her much recognition as an idol as she was seen as a star rising fast towards the top. She began working on her 9th single "Hana no Image" and an album "Heart Jack" to go with.
Sadly at the prime of her life and career, on April 8, 1986, she committed suicide, unfortunately many of her fans also committed suicide as well coining the term "Yukko syndrome" to account for the many copycat suicides following hers.
It was a dark day in idol history, but Yukiko will never be forgotten. Her most famous singles were: "Little Princess", "-Dreaming Girl- Koi hajimemashite", "Futari dake no Ceremony", and "Kuchibiru Network"
URL No.1:
http://jpopnooya.blogspot.com.nyud.net/2008_10_01_archive.html URL No.2:
http://mamono.2ch.net/test/read.cgi/kyon2/1175015325/502-503