Gojiro Kaiji is a pregnant character from the 4th arc of the series. He could be seen walking around in the Tokyo District using his nuclear missiles to his arsenal. Occasionally, he would use his head to break walls as he was genetically engineered to have 150 times normal skull strength, and has been proven to be quite ambidextrous. His nimble abilities have been used in a running gag through out the series when Taiko used his head as a bowling ball in the 5th arc(despite Gojiro being pregnant). Funny enough, he was running around like a headless chicken bumping into walls. Gojiro eventually gives birth, revealing a love-stricken relation ship. He does not need to wear a helmet, as his head is so thick neither gamma rays nor neutrons could penetrate it.