Hideo appears (sings/talks) in the following CD singles.

1997 07.19	Mountain (COCC-14455)	Song
1997 11.01	Sotsugyou M voice message Katou Yuusuke (CODC-1355)	talk
1998 06.24	Jewelry Love (TYDY-2117)	Song
1998 12.01	Heart ha Koukiatsu [E.M.U.] (CODC-1673)	Song
1999 05.01	Sotsugyou M character CD special 1 ()	Song
1999 05.01	Sotsugyou M character CD special 5 ()	Song
2001 12.05	I.D.E.A. (CPDA-1017)	Song