The voice is too different. Can't be Ukigumo.

You're certain, riiingo? I think it sounds a little bit like him at parts... I'm not giving up hope!

I think you just have a wild imagination fluffie. :P

It's 浮雲(Ukigumo).
"Uki Ataru" is just a translation mistake.

浮雲(Ukigumo)
鰰澤亜人(Inazawa Ahito)
渡辺等(Watanabe Hitoshi)
http://www2u.biglobe.ne.jp/~gaspard/nochoice/index.html
高桑英世(Takakuwa Hideyo)
http://www.face-music.co.jp/3_player/takakuwa.htm
斉藤ネコ(Saito Neko)
タブ(Tabu)
椎名林檎(Shiina Ringo)

Takakuwa played 篠笛(Shinobue)
http://ja.wikipedia.org/wiki/%E7%AF%A0%E7%AC%9B
Tabu (=Tabu Zombie from Soil & "Pimp" Sessions) played Didjeridoo
http://en.wikipedia.org/wiki/Didjeridoo

Emil Scherbert delivers!

Ahhaha, thanks Emil! That just made my day.

So, now we have it. Ukigumo's known contributions to KSK:
- Meisai: guitar -- proving he can indeed strum :p
- Ishiki: guitar
- Torikoshi Gurou: mouth rhythm
- appearance in the Meisai video

Nagaoka Ryousuke also known as Ukigumo was certainly credited in Utaite Myouri's booklet.

Photo 1: Mori-pact disk booklet
長岡亮介(Nagaoka Ryousuke) was credited in
外国語レクチャー(Foreign language lecture) and 絵柄文字(Letter design)

仏 = French, 葡 = Portuguese

Photo 2: His letter design was assumed as "森"(Mori) and "亀"(Kame) on disk.

You know what's funny though? Both of his KSK appearances are relegated to the piano on Electric Mole. I prefer the guitar on the EM version Meisai as it helps change the whole feel of the song. However, I do prefer Uki's work on Ishiki (single version is my favorite). I really like the natural harmonic part for some reason.

Also, if anyone cares, SR met Mikio Hirama through Mukai. Hirama met Mukai when the two were both working on hàl's Blue album.

How a thread about Shiina-Number Girl (and to a much lesser extent, Zazen Boys) devolved into an "all about Uki" thread is shameful =p