Riiko personifies the Raillord of Tobu Railway 5, a British-built Class B1 4-4-0 steam locomotive originally produced by Meyer-Leecock Manufacturing in 1898. After decades of service on the Toubu Misezaki Line until 1966, her preserved form now resides at Tokyo’s Tobu Railway Museum. Her attire mirrors the locomotive’s historic palette: green hair pinned back with a clip contrasts a black uniform featuring red-trimmed sleeves, a tailored jacket, shorts, white gloves, and a conductor-style hat.

Detached in demeanor yet fervently devoted to entomology, Riiko frequently redirects attention from routine duties to insect observation, fostering perceptions of capriciousness. This reputation belies her analytical ingenuity when merging entomological knowledge with engineering challenges—exemplified by her creation of beetle-inspired anti-slip omamori charms to improve rail adhesion. While she approaches mundane tasks with dispassionate efficiency, her focus sharpens dramatically when entomological principles apply, revealing methodical problem-solving skills. Colleagues alternately critique her sporadic engagement and admire her unfiltered passion, acknowledging her niche expertise as an unconventional asset in maintaining her role as the Misezaki Line’s steadfast Raillord.