Bukiko Kotobuki is Ao Gennai's best friend and classmate. She possesses extensive model kit knowledge, regularly supplying Ao with the latest parts and accessories. This expertise aids Ao in understanding and maintaining the Frame Arms Girls, and Bukiko further demonstrates her deep involvement by designing custom weaponry for them. Despite her passion, she does not own any Frame Arms Girls herself. Her name forms a deliberate pun referencing the real-world manufacturer Kotobukiya.

Visually, Bukiko has dark green hair styled in ribbon-tied pigtails and a distinct snaggletooth. She wears the standard Wakaba Girls' High School winter uniform, featuring a pre-painted checkered skirt available in two variants: one optimized for standing poses and another designed for seated positions. Her accessories consistently reflect her hobby, including multiple nippers, a school bag adorned with the HEXA GEAR mascot "Sana-chan," and a nipper-motif smartphone case. Her expressions include smug, grinning, crying, poking her tongue out, and smiling.

Within the narrative of *Frame Arms Girl: Kyakkyau Fufu na Wonderland*, Bukiko appears alongside Ao and the Frame Arms Girls. She participates in sequences where the group watches their past adventures, wearing her school uniform. Additional footage shows her engaging in karaoke with Ao. Her established role as Ao's supportive friend and modeling resource remains consistent throughout the film, with no significant expansion of her backstory or character development depicted.

No substantial changes to her background, personal history, or character progression exist in other official media extensions beyond her core supportive role and modeling expertise as established in the television series and film.