Osu is a blue-haired young man who stands at 167 cm (5'5"). He is pale, presumably from his ill disposition. He often wears a long-sleeved turtleneck, pants, and a sort of mid-arm length, two-toned, v-neck robe, which he ties at the waist with a fabric belt.
He is incredibly kind and polite, even portrayed as an angel in the cartoon. For example, when Naga was depressed that he didn't feel that sad when he heard Venom and Tracey had died, Osu told him that, "You're trying to feel sad and to remember them both. Only a good person would do that." Even with his kindness, he doesn't hesitate to speak out his mind.
Because of his personality, he gets along with almost everybody, except for his parents.
Contrast to his angelic personality and looks, he likes looking at porn magazines. In fact, his hobby is collecting erotica magazines. He has a shelf packed with them to the brim.
He comes from a wealthy family but did not contact them due to a poor relationship with his father. Number 1. was also not on good terms with Osu's father, to the point of throwing a chair at him, even though he and Number 2. cared for Osu when he was a child. During some point, Osu moved away and lived with Number 1. and Number 2.
When SPOON was in danger of shutting down because KNIFE had 'disappeared', it was Osu who intervened and made FAKE KNIFE, so SPOON can maintain its purpose.
- Human Drug: Every part of his body is some sort of an addictive drug. These drugs will cause emotional instability, hallucinations, and other side effects if one is exposed to them for an extended period of time. He can also use this abiltity to numb people's pain, such as breathing onto them.
He has taken care of him since he was a child due to him being his adopted child, they seem to be on good terms with each other.
Along with Number 1. he is taking care of Osu, it is unknown whether Number 2. is also his adoptive father.
- He has an older sister, who is married and appears briefly in the special New Years episode.
- Osu has a lot of pillows in his bedroom and they contain dried herbs inside.
- Osu is very sick and has been for his whole life.
- Osu isn't allowed in hospitals due to his ability.