Nodaiko, originally named Yoshikawa, works as the art teacher at Matsuyama's middle school alongside Botchan. Botchan assigns him the nickname "Nodaiko," evoking a male geisha who flatters and entertains powerful figures, reflecting his obsequious support of the vice principal, Red Shirt. Though both hail from Tokyo, Nodaiko lacks independence and aligns uncritically with Red Shirt's schemes. He acts as Red Shirt’s accomplice in manipulative plots against Botchan and Porcupine, including a deceptive fishing trip to sow distrust between them.

Nodaiko further demonstrates loyalty by aiding Red Shirt’s plan to evict Botchan from his lodgings. He pressures the landlord, Ikagin, to fabricate complaints about Botchan’s behavior, intending to claim the room for himself and showcasing his willingness to exploit others under Red Shirt’s direction.

During the novel’s climax, Nodaiko accompanies Red Shirt to a hot-springs-district brothel. There, Botchan and Porcupine ambush and physically assault them as retribution. Nodaiko’s submissive, cowardly nature emerges as he offers no resistance.

Nodaiko’s background, motivations, and development remain unexplored beyond his sycophantic role. He functions statically throughout, solely facilitating Red Shirt’s central conflict, with no indication of his fate after the brothel confrontation.