Joe is defined in the series guidelines as a "tragic, troubled loner," and indeed he seems to be a magnet for disaster. He lives to take revenge on Gallactor for killing his parents back when he was eight years old. It appears his father, Giuseppe Asakura, was a high-level leader in Gallactor until he either ran afoul of organizational politics or developed a conscience and decided to seek asylum with the ISO. It's unclear what his motives were, but he was waiting to meet with Dr. Nambu when a Devil Star fatally shot him and his wife, Katarina. Joe was nearly killed by the Devil Star as well, but was rescued by Dr. Nambu and later trained for the Kagaku Ninjatai. For a long time, he had no clear memories of his parents' deaths or Gallactor's motive for their assassination.

Joe acts as a counterbalance for Ken—impulsive, impatient and furious when Ken is lucid; stable and sensible when Ken is acting irresponsibly. Joe is a top-class marksman and acts as chief gunner for the team. His preferred mode of action is "Shoot it now and improvise the rest," but he is by no means a cold-blooded murderer. He's good at hot-wiring his way out of tricky situations. Excels at throwing darts and knives; every member of the team carries feather shuriken, but use of these weapons becomes Joe's trademark.

Cover occupation: Private race driver; drives in endurance rally and stock car races. Lives in a small trailer, which he tows from race to race.

In the second series, he becomes a cyborg.
(Source: chronicsite)