Kyōko Koizumi
Horikawa has written and composed songs for popular artists including Miki Imai, Jun'ichi Inagaki, Yukiko Okada, Kyōko Koizumi, Yuki Saito, Noriko Sakai, Miho Nakayama, Yū Hayami, Chiemi Hori, Saori Yagi, and Marina Watanabe.