IM@S seiyuus singing/acting in other games/anime.
Rie Kugimiya voices Happy in Fairy Tail, she also voiced in Persona 4, I just don't know who the character she voiced was, Taiga in Toradora. She's...like, famous.
Nunu and Saori star in Hibike! Euphonium, along with Tomoyo Kurosawa who voiced Kumiko, the lead, and Miria in CG.
Pon-chan (Asami S.) gave sampling vocals to the Kagamine sisters. Aya voiced many characters, I just don't remember them.