Mr. Arashiyama, an engineer employed by business executive Mr. Kuroshio, was married with a son named Hayato; the family owned a dog. During a coastal drive after a fishing trip, he witnessed a car accident involving Mr. Kuroshio and his wife. Acting compassionately, he aided the injured couple and guided them to a nearby abandoned mansion for shelter during a thunderstorm. Inside the mansion, the group encountered a mysterious skull-masked figure who declared himself the captain of a phantom ship and spoke of seeking vengeance for past tragedies.

Following this unsettling encounter, the family returned to their routine life. Shortly afterward, their coastal city faced an attack by a giant robot identifying itself as an emissary of the phantom ship. Mr. Arashiyama sustained fatal injuries during this attack. In his final moments, he conveyed critical information to his son Hayato, revealing a significant secret concerning Mr. Kuroshio's betrayal and the true nature of the phantom ship threat. This revelation became the catalyst for Hayato's subsequent quest for justice.

His character design reflected the manga style of the era, featuring a strong jawline and distinctive facial lines. His actions, particularly aiding others during the initial accident and his final revelation to his son, positioned him as the catalyst for the narrative's exploration of corporate malfeasance and familial bonds. His death established the primary motivation driving his son Hayato's actions throughout the remainder of the story.