Yukiko Okada radio recordings

すごいです〜！　ユッコちゃん、一番好きです。どもありがとうね。^_~ Thank you so much for sharing these! I will certainly be listening to these, downloading these and uploading them to archive.org. I currently have a lot of translation projects on my plate, but in the future I can see myself doing some English subs for these interviews. Yukko forever~!

Thanks again for sharing these links, I've downloaded all of them and plan to upload them to archive.org asap.

lammyvox  Sakura Stardust

Some more information. The Japanese Wikipedia articles have citations which can be verified. I left all titles in Japanese untranslated.

Some uploads by bien-0501 are from the radio show 夜遊びしナイト！ According to the Japanese Wikipedia article, this radio show aired on Sundays from October 1985 to April 1986.

This show was preceded by 奈美子・有希子・小緒里のドキドキラジオ, which aired from April 1984 to October 1985 (Wikipedia). Bien-0501 has uploads of this show.

In turn, this was preceded by サトミ・ヒトミ・ユキコの何かいいことないか仔猫ちゃん, which aired from October 1983 to April 1984 (Wikipedia). An episode is available below. Notably, this show aired pre-debut. 

All these shows were produced by Sun Music.