In the story, Hiyori's grandma passed away. For his daughter who cried every day, Hiyori's papa built a grandmother-model robot named Wasimo. The nostalgic "katakatakata" sound Wasimo makes when it walks comes from the same false teeth that Hiyori's grandma had. Wasimo walks faster than a snail, but slower than an excited snail. Still, Wasimo can actually run faster than a speeding bullet train. The story follows this strange Wasimo as it meets all sorts of people and has all sorts of experiences.
[Source: Akiba Souken]