Koseki Bijou (古石ビジュ―), commonly known as Biboo, is a female English-speaking Virtual YouTuber associated with hololive. She debuted in 2023 as part of hololive -Advent-, the third generation of members of hololive English, alongside Shiori Novella, Nerissa Ravencroft, Fuwawa Abyssgard and Mococo Abyssgard.