Hiyori's father, known as "Papa," created a robot modeled after Hiyori's grandmother to comfort his daughter, who cried daily, distraught after her grandmother's passing. This robot, named Wasimo, incorporates distinctive features reminiscent of the grandmother, notably producing the nostalgic "katakatakata" sound while walking, originating from the same false teeth Hiyori's grandmother used. Wasimo moves faster than a snail but slower than an excited snail, though it can also run faster than a speeding bullet train. Wasimo's creation serves as a central element in the narrative, facilitating various interactions and experiences for the characters.