Hayato is an attractive young man appearing to be around 18-20. He has shoulder length white hair which was originally black until taking a series of serums and piercing purple eyes. For clothing he wears a dark suit with a feathery collar, a plated chest piece, and belts around his waist.
Hayato possesses a cool headed disposition, shown that works even in the most extreme circumstances shown when he defused a bomb while in the middle of combat. However, Hayato is shown to be rather quiet and nearly without affection. This is primarily because of the restraints he put on himself so that he does not lose control of himself. He has a distinct sound he makes when surprised: 'Dowao!'
Hayato after the numerous injections on his body had gained numerous enhancements allowing his brain to process functions more efficiently than a normal human. This increases his intelligence, mental and physical strength, and healing factor. However, the stimulants cause numerous side-effects such as increased aggression that cause a murderous spree. To keep himself from doing more than necessary damage, Hayato has to use tranquilizers that often knock himself out. These even go to injectors installed into cockpit of his Getter Machine. But even the tranquilizers can cause poisoning which can severely damage Hayato's body.
Hayato at the earlier parts of life lived happily with his parents and was even part of his school's basketball team. Three years prior to the series, Hayato lead an anti-social revolutionary army called the Army of Hayato. Ready to overthrow the government, Hayato and his revolutionaries bore witness to the start of the Idea. The monsters had wiped out most of Hayato's men with Hayato as the only survivor. Going through numerous drugs and traumas, Hayato decided to join GETTER to fight the Idea.