Nishiwaki is a supporting character in Sukeban Deka: The Movie who serves as a former caretaker and contact for Yoko Godai, the second Saki Asamiya. He works as an agent connected to the Dark Inspector and provides crucial intelligence and technical support during the mission to stop Hattori. He reveals that Hattori is actually the supposedly dead revolutionary leader Jishu Kita, who is now backed by a shadowy political fixer known as the Mastermind. Nishiwaki also delivers an upgraded weapon to Yoko: a quadruple‑weighted yo‑yo with sixteen times the power of her previous one, though its use risks irreparable damage to her arm. His personality is calm, resourceful, and quietly supportive, with a dry sense of humor evident when he jokes at the film’s end that this time the farewell is real. He does not undergo significant personal development in the movie, remaining a steady ally who provides essential aid at a key turning point. His relationship with Yoko is built on a history as her caretaker, and he is shown to respect her abilities while also urging caution. In terms of abilities, his primary contributions are his knowledge of covert operations, his access to upgraded technology, and his knack for delivering timely information. He does not engage in direct combat, instead acting as a strategist and quartermaster for the team.