Manufactured by Hishii Industries (Model number: HL-98). In some sources, it is also written as Hercules H21.

Heavy-duty construction laborer. It is more humanoid than the Tyrant or Bulldog, and has more dexterity. The cockpit is also fully sealed. It is the successor to the HL-97 (Bulldog). A telescopic periscope snorkel mechanism is built into the top of the head, and it performs almost as well as a dedicated labor for underwater work.

The catchphrase is "The burning man's general-purpose labor."

In the first half of the manga, the setting had not yet been solidified, so the head has no protrusions and is drawn somewhat flat.