Nin-Nin is a dwarf ninja consistently clad in hooded attire. He serves as a devoted companion and protector to the female protagonist Miko Mido, yet exhibits voyeuristic inclinations—observing her during baths or intimate moments. His visible enthusiasm surfaces when encountering Miko in compromised states, such as partial undress or during sexual encounters with adversaries or supernatural beings. Despite these tendencies, he remains steadfast in his protective role, intervening when threats arise. His aid occasionally wavers when distracted by meticulously documenting Miko's experiences for personal archival purposes. This dual role persists unchanged across all narrative appearances, with no evolution or expanded background provided.