Kazarin killed a mother dog when testing her soon-to-be-beast-fighter wolf, Garus. The puppy who lost his mother was then kept by Daijirou. Kenichi didn't like his brother keeping a pet dog. When Voltes was fighting Garus, the puppy recognized the beast fighter as the former wolf who killed his mother.
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Voltes V Learns a Lesson from a Puppy and we will let you know when it becomes available.