Gotou (後藤, lit. Gotō) is an 'experimental' parasite created by Reiko. His body is composed of five different parasites, whose power he can utilize to the fullest extent, making him one of the most powerful parasites in the story. He is the main antagonist of the series.
During his first appearance when he assaulted the Yakuza, Gotou wore track shoes, gym shorts and a tank top. He had short brown hair, with a round face, and kept his eyes closed most of the time.
To hide from the authorities, he then changes his look to have a longer face with sharp features. He has a large muscular and toned physique, which is often covered in suits. In the anime, his second appearance seems older than his manga counterpart.
owards the end of the series, Gotou transforms into a 3 meter tall monster. The outside of his body gains a gray tinge to it, and has the appearance of exposed muscle. His face becomes sharper, sporting pointed ears, four eyes and a mouth full of several rows of fangs. He also has four arms, a scythed tail, and digitigrade legs reminiscent of a dinosaur's.
Personality
Gotou is one of the more intelligent members of his kind. He has shown a superiority complex over the human race, believing they are nothing but trash. He shows no remorse in combat, dismembering his opponents without a second thought. He has shown to be a patient person, waiting for his turn to attack and observing his enemies, and even allowing Shinichi to leave so that he may recover. Though he believes himself to be above humans, he still considers himself nothing other than a "wild organism" that "lives to fight".
Though he is arrogant and dismissive of humans, he is respectful enough of either Reiko or Hirokawa to stay under the human's control with the other parasites even when Reiko is suspected to be dead, only going solo during the city hall battle after Hirokawa chooses to give up. He is also willing to allow Miki to take over the body and hunt or fight despite Miki's lesser ability, stating he only needs more experience. Likewise, he willingly praises his opponents for decent strategy, though he finds being injured by a single human rage-inducing.
He displays some respect towards Reiko, contemplating her plans with Hirokawa and later acknowledging that she might have been a formidable opponent if they fought. Additionally, in the manga he is notably cordial with her, as he asks after her while she is on maternity leave and greets her when she returns from it.
In his transformed state, his thoughts become more primitive, focused solely on battle and survival. He was also more aggressive and became easily angered in this state, something that played a part in his downfall.
After being absorbed and escaping Gotou, Migi also reveals that due to the other parasites in his body having consumed heads as well, he feels five times the bloodlust and desire to kill humans that a normal parasite would, making him a perfect "killing machine".
