Lemon Sunomono, whose real name is unknown, is a young girl spy and the deuteragonist of the film Crayon Shin-chan: Fierceness That Invites Storm! Operation Golden Spy. She is seven years old and a member of "Action Spy," an ally of Action Mask. Together with Shin-chan, she aims to reclaim the "Action Power Capsule" from the evil scientist Dr. Hegaderu. Already possessing top-notch spy abilities, she trains Shin-chan to become a spy. Due to her strict adherence to the idea of absolute obedience to family, she is bewildered by the vastly different dynamic of the Nohara family.
In reality, she is a spy from the Republic of Sukashipestan, tasked with retrieving the "Mega Hegader II" developed by Dr. Hegaderu. She approached Shin-chan because she needed him for infiltrating the Hegaderu Institute.
She cheated Shinnosuke by betraying him, she said that "We need to help Action Mask and get the Megahegaderu", however her mission was to help the evil queens of Republic of Sukashipestuan. When she realized her mistake, she got united with Shinnosuke and destroyed all dreams of the evil queens and her parents.
As she spends time with Shin-chan, her perspective changes. Ultimately, she betrays the Republic of Sukashipestan and, together with Shin-chan, consumes the Mega Hegader II and takes decisive action to thwart the ambitions of Naarau and Yoosuru. After the incident, she and her family seek asylum in the Kingdom of Haederuna.
