Koji Kabuto - Fictional Character Biography and Personality - Grendizer

In the second Mazinger-Z spinoff Grendizer, Koji is reduced to being a sidekick to the series' main hero Duke Fleed - a long stint that many Mazinger Z Japanese fans did not appreciate.

For much of the early series of Grendizer, giant enemy robots are left to Duke Fleed to destroy. On numerous occasions, Duke Fleed has to rescue Koji, who ends up being injured or gets his puny saucer miserably wrecked. When this saucer gets destroyed once and for all, Koji designs a more powerful aircraft called the Double Spazer which gives him a much more active role in battle.

For whatever reasons, Mazinger Z was hardly mentioned in Grendizer. When Koji reappeared in a theatrical get-together with other super-robot family members, he flew the Double Spazer, as if Mazinger Z could no longer be effective against the megamonster of the moment.