like there's so much of producers do the vocals of their songs.
For example, as I know are syudou, surii, Chinozo, kujira, Ayase, Aqu3ra, Harumaki Gohan, Kanzaki Iori, Keina Suda (balloon), Kenshi Yonezu (Hachi), PinocchioP, MikitoP, R-Sound Design, Mafumafu, KIRA, wowaka, Eve..