Last Samurai is a supporting character in Arakawa Under the Bridge who runs the community's barbershop under the bridge. He comes from a samurai family and carries a katana that was passed down through his ancestors as an heirloom. Before moving to the riverbank, he worked as a hairdresser and became famous enough to be featured in a magazine. Despite this success, he felt dissatisfied with his life and lost his way as a stylist. After meeting the village chief, he decided to forge his own path and moved under the bridge, where he adopted a topknot hairstyle and became what he calls a river barber.

His personality reflects a strong dedication to the samurai code, and he approaches his craft with seriousness and discipline. He is capable of cutting anyone's hair in a matter of seconds using his sword, performing the task with such incredible speed that ordinary people cannot perceive his movements. One notable exception is Sister, who is able to see through and evade his technique. He introduces himself with a special name-related catchphrase when using his sword for haircuts.

His role in the story is to serve as the community's barber, providing haircuts for all the eccentric residents living under the Arakawa Bridge. His motivations center on finding personal fulfillment through his work and embracing his own path as a hairdresser, free from the expectations of conventional society. He values the freedom and purpose he found under the bridge after meeting the village chief, who helped him realize that he could walk his own way. His key relationships include the village chief, who inspired his decision to live under the bridge, and the other residents whose hair he cuts, making him an integral part of the community. Over the course of the story, he remains consistent in his samurai-like dedication to his barbering craft, having found a meaningful place where he can practice his skills on his own terms.