Nin-Nin, a dwarfish ninja of the Miroku clan, serves as the protagonist’s loyal but lecherous companion, often comically reprimanded for attempting to spy on female characters in vulnerable moments. He documents the protagonist’s battles with a video camera, framing it as tactical study while subtly compiling in-universe records of her exploits. His true identity, revealed in later manga arcs, identifies him as a young Shikima demon masquerading in dwarf form. This heritage grants him the ability to shift into an adult guise, which inadvertently draws romantic interest from others. Though his childlike appearance prompted censorship in international releases—scenes implying sexual activity were excised—his dwarf status, not age, defines his physique.

Born to a human mother who died during his traumatic birth after being assaulted by a Shikima, Nin-Nin’s deformed demonic features remain hidden beneath his mask. This tragic origin contrasts sharply with his role as a comedic figure, layering his antics with underlying pathos. Despite unreciprocated romantic feelings toward the protagonist, their relationship stays platonic, with Western adaptations removing gags involving his attempts to grope or peep on her. His loyalty proves steadfast in combat, balancing mischief with battlefield reliability.

Later narrative arcs delve into his demonic lineage, particularly in spin-offs and manga conclusions, where his adult form catalyzes others’ desires. Regional censorship diverges significantly: international versions obscure his age context and demonic traits to comply with local laws, while original Japanese portrayals retain his unfiltered comedic and supernatural elements within legal constraints.