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

1995 01.21	Elles Cinq II: Tiny Heart	Talk
1995 01.21	Elles Cinq III: Love Drug	Talk
1995 01.21	Elles Cinq IV: Nostalgic Lover	Talk
1995 01.21	Elles Cinq V: Tears no Kataomoi	Talk
1997 07.19	Mountain (COCC-14455)	Song
1997 11.01	Sotsugyou M voice message Takagi Shimon (CODC-1353)	talk
1998 01.21	Forever Love [ZMAP] (KIDA-160)	Song
1998 12.01	Heart ha Koukiatsu [E.M.U.] (CODC-1673)	Song
1999.01.??	Yuukyuu Gensoukyoku character series 8 (PCDB-016)	Song
1999 05.01	Sotsugyou M character CD special 1 ()	Song
1999 05.01	Sotsugyou M character CD special 3 ()	Song