Sonic the Hedgehog - Remix
From Sonic Retro
Is yasu Mitsuyoshi: The Last Stand
From this page: http://sonic.sega.jp/sonicadv/snd/other_05.html
あ、あと当初セガの歌えるボーカリスト（そのまんま）光吉が歌う予定があったんですが、諸々の事情で見送りになったんです。
This sentence, from Hataya, mentions Mitsuyoshi. Google translate seems to hint that he was replaced, by the translation doesn't seem as accurate as usual. Nevertheless, the answer is right here for your convenience.
If it's not him my best estimates are Yasushi Hasegawa and then Yasuhiro Tamaki (both from Sound AMS), but neither is immediately promising. E102 03:09, 28 November 2012 (UTC)