The Hololive Koseki Bijou Nendoroid captures the essence of a tiny idol with a gem-inspired aesthetic. The figure stands on a clear oval stand, with a chibi form about 100 mm tall. The sculpt features oversized head, large sparkling eyes, and a glossy jewel-toned palette of pinks, purples, and aquamarine. The outfit is a ruffled sailor-inspired dress with layered skirts, metallic gold trim, and a crystal brooch at the chest. Removable accessories include a jewel-like microphone, extra face plates with different expressions, and a posed hand. The paint application uses translucent accents for the sleeves and cape, giving a luminous, gemstone-like finish. The base is compatible with standard Nendoroid stands; compact, stable, easy to pose.

Koseki Bijou is depicted as a playful holo-idol who channels celestial light through music and gemstones. In her in-universe story, she travels between digital venues and real-world stages, collecting tiny fragments of stardust that manifest as sparkling jewels in her wardrobe and performances. She communicates with fans through bright, melodic streams that feel like lullabies and dance numbers performed under moonlit skies. Bijou's character emphasizes kindness, curiosity, and a sparkling sense of mischief, turning every broadcast into a miniature festival. Her backstory explores friendships formed across virtual corridors, the pursuit of perfect rhythm, and the joy of sharing colorful moments with a growing audience.