Kumiko Yokote (横手 久美子, Yokote Kumiko; born April 21, 1973 in Chiba) is a Japanese voice actress and singer who works for Power Rise under the alias Hyo-sei (氷青, Hyōsei). For adult works, she goes by the name Elena Kaibara (海原 エレナ, Kaibara Erena). Hyo-sei released her first album titled Fuyu Hanabi (冬花火) on April 21, 2010.
Source: “Hyo-sei”, English Wikipedia (CC BY-SA 4.0), excerpt