Hayataro is a robotic poodle pet holder owned by Hachimaru, though its AI has cat-like tendencies. It wishes to obtain a more dog-like AI. After Hachimaru became a samurai, he transformed Hayataro into a Key Holder.
Hayataro started out as a companion Holder for Hachimaru, programmed by him to compensate for his inability to socialize with others. Though he sometimes failed to properly support his creator due to his master's imperfect programming skills, Hachimaru nonetheless treasured Hayataro's company.
One day, Hachimaru tries to play fetch with Hayataro using a ball, but the Holder brings back a Daruma doll instead, unaware it actually a sleeping Samurai. After the chance meeting with Hachimaru's idol, things became dangerous when Hachimaru's father was taken hostage by a ronin that attacks them. When the rogue warrior managed to disable Daruma, Hayataro attacked the ronin, only to be broken in two. Before Hayataro broke down completely, Hachimaru committed seppuku and triggered a Locker Ball the Ronin had stolen. After transforming into a Samurai, Hachimaru was able to use his new powers to transform Hayataro into a full size Holder. Given a new shape and enhanced abilities, Hayataro helped his reborn master take down the Ronin.
- Shapeshifting: Like all Key Holders, Ushiwakamaru is able to shapeshift his body into various forms.