Ratio is a doctor and Hamatora PI who helps Birthday out on handyman business. Together they are known as the Handyman duo. He has been friends with Birthday since they were young. His ability activates when he removes his eye patch, allowing him see a person's body structure. He then uses brass knuckles, which he hides under his gloves, to hit their weak points.
Ratio is pale-skinned with slightly dishevelled dark blue hair. He has blue eyes which match the colour of his tie.
Ratio wears a white shirt and a long white coat, indicative of his job in the medical profession. He wears black gloves and a dark blue tie, which he tucks into his shirt pocket. He wears an eyepatch over his right eye.
Ratio is the cool headed type. He likes getting work done quickly and constantly scolds Birthday for horsing around. It seems as though he greatly values physical health; he is very critical of muscles and body structure. In Episode 1, "Egg of Columbus", he comments that the criminals are very lucky, because even in prison they can do muscle training. He also seems to have a very strange sense of humor and understanding, as he frequently makes remarks such as "I see, so that's what they call a 'hot stone spa'." when Honey offers to tie Birthday to a rock and sink him in the hot springs as revenge for hitting on her on Episode 5. Oddly, he ends up being portrayed as slightly childish whenever he tags along with Birthday for his handyman job, as seen in Episode 8. Although he is usually calm and shows little emotion, Birthday's jolly personality and his troublesome antics result in situations where Ratio raises his voice out of disbelief (often portrayed as comical) and anger.
As a child, Ratio foresaw the death of many people, due to his ability. Because of this, many people called him the 'Prophet of Death'. In order to protect himself from being hurt, Ratio separated himself from others including his classmates. However, around elementary/middle school, he met Birthday, whom he predicted to die very soon. Birthday decided to help Ratio and bet that he wouldn't die, and if he lived, Ratio would have to die. Miraculously, Birthday survived and told Ratio that the 'Prophet of Death' was now gone. Birthday and Ratio continued being friends, as Birthday vowed not to die until Ratio could fully overcome his past. Because of this, Ratio also vowed to protect Birthday at all costs.
It was revealed that shortly after Birthday left Facultas Academy he soon followed.
Ever since Birthday 'killed' the 'Prophet of Death', the two have been best friends, despite their contrasting personalities. Ratio is generally the one who keeps Birthday in line, while Birthday balances out Ratio's gruff personality. The two work together very well during battle. Ratio has been shown to care for Birthday, for example, when he tried to defeat Nice in order to save Birthday and when he promised to cure him of his illness.
She has been friends with both Birthday and Ratio since high school. After the events of season 1, Chiyu went missing. Ratio and Birthday spent their extra time looking for her until they discovered that she had joined Freemum, an organization for 'stray' minimum holders that didn't attend Facultas or wish to abide by their rules.
Powers & Abilities
Ratio's Minimum allows him to spot the weak points of his opponents, which he then uses the golden gauntlets to land a critical blow on his enemies. The requirement for this ability is simply taking off the black eyepatch on his right eye, which activates the Minimum instantly.
- Perspective Minimum (Usual Suspects Minimum in the manga): Ratio has the ability to observe the muscle structure of his opponents with his right eye, which allows him to easily find weak spots. It seems that he is also able to perceive other people's orientation when they are not moving.
- Gold Arms: Ratio wears solid gold gauntlets on his arms, which allows him to pack a punch during battle. The reason why he wears such a thing is not yet specified.
- Ratio is completely mysophobic and enjoys cleaning as a hobby.