Koichi

Shido is depicted wearing a black pinstripe suit. Inside the suit, he wears a white dress shirt along with a yellow tie. He also wears black-framed glasses and brown dress shoes. Shido's body frame is very thin and he has various expressions seen throughout the series. This includes switching from a peaceful expression to one with intense hate and scorn. His outwardly appearance is that of a fragile man, and this appearance often aids him in gaining undeserved trust from various characters throughout the series who are not aware of his debauchery and evil intentions.

He appears to be a kind and caring teacher, but in reality, he is sadistic and allowed the students he had deemed "weak" to be bullied. There were even instances where he himself would engage in bullying. When the zombie apocalypse occurred, Shido used his charm and charisma to convince the majority of the surviving students to join him. After having brainwashed them, Shido reveals his true intentions by having his followers engaging in sexual intercourse. He does this because he wants them to repopulate the planet. This way, he will rule and be served by mindless followers. His strong charismatic authority and quasi-religious mystique render him a David Koresh-like figure.

Shido has shown in several instances that he is quite ruthless, being willing to do underhanded things, such as lying and manipulating, in order to get ahead. He has also shown that he is quite arrogant, believing himself and the students that follow him to be superior to everyone else.

It should be noted that Shido is a coward. He is terrified of "Them" and immediately flees whenever he sees them. He also cowers in fear when Hirano points a gun at him.

His behavior throughout the series can be officially classified under standard psychiatry/psychotherapy guidelines as extreme sociopathy. His flawed psyche most likely developed as a consequence of growing up in a broken household that was dominated by his abusive father. So abusive was his father that his mother commited suicide when Shido was only a young boy; this tragic event in his past must have strained his mentality and made him into a man without humanity.