Ninju

The Ninju are clever mice that serve Tengen Uzui, having been specially trained to assist him and those around him (Chapter 76). Despite their small bodies they are strong enough for each mouse to carry one Nichirin Sword, and they can move through tight gaps that people simply cannot fit into.

Their faces taper to sharp snouts beneath big, round, pink-colored ears. The coat is largely grey, though black covers the legs and forepaws, and where a normal mouse would be slight, these creatures bulge with muscle. To match Tengen's own style, each sports a pale grey headband studded with a row of three sizable pink jewels.

The Ninju's value lies in delivering weapons discreetly thanks to their small size and surprising strength, letting them slip swords to Tengen and his allies in places as awkward as a busy brothel. Tengen's training gives them the power to carry a blade despite their stature, and their sharp intelligence lets them navigate between locations and bring each sword to its proper owner, which makes them a real asset during operations.

During the events at the Ogimoto House, an impatient Inosuke Hashibira called on the Ninju to fetch his swords, pleased that Tengen had lent him such helpers, then armed himself and headed out (Chapter 76). Later, in the fight against Daki's sentient sash, a Ninju carried Zenitsu Agatsuma's sword to the battlefield so he could strike at the demonic obi, after which the mice were seen flexing their muscles once the skirmish ended.