Kou Mariya (コウマリヤ) is a female English-language VTuber. Initially debuting as an independent VTuber in 2020, she joined V4Mirai in 2023 as part of its second generation "Petalight", alongside Mono Monet, Yae Yugiri, and Biscotti.
In October 2025, she retired following a failure in contract negotiations with V4Mirai. She initially expressed wishes to return as an independent VTuber, but the creator of Kou Mariya ultimately announced that she will be retiring the character and will instead be continuing as Emiliya Fell.
In May 2026, V4Mirai restored her IP and accounts to her creator, and Mariya returned to being an independent VTuber once more.

Vampire × VTuber × VSinger × V4Mirai = #V4MPIRE
First your neck and then your heart!~