Okuyasu is prone to punching people whom he dislikes This curiosity extends to having an habit to try to learn the bottom line of anything, notably asking Josuke persistently why he helped heal his wounds when Keicho shot them both and why he couldn't heal his own wounds, which is one of the reasons why he has such difficulties at making decisions when opponents try to manipulate him. Okuyasu is a very curious person, showing deep interest in any new sight, which has led him toward Tonio Trussardi's restaurant and a crop circle where Mikitaka Hazekura rested. However, Okuyasu eventually grows out of it: at the end of the part, when Okuyasu was hanging between life and death, he took the decision to live and save Josuke.

His inability to think was exploited on three occasions, and during all this, he was easily psyched out by his opponent. This results in him repeatedly and openly stating his lack of intelligence. Constant reliance on his big brother Keicho Nijimura and belittling from him made Okuyasu unable to make decisions that do not come out of instinct and is self-conscious about this limitation. Okuyasu has been known to be 'not good at making decisions' and being generally dimwitted, although he has moments of genuine ingenuity. Okuyasu frequently acts out of impulses and rarely takes the time to observe or reflect in a fruitful manner. He consistently shows his emotions, which are more extreme than for the average individual, being ecstatic when he is happy, in tears when he is sad, and enraged when angry. Okuyasu is a very extroverted and impulsive man, acting by his own words 'with his heart'. The word that describes Okuyasu the best could be 'childish', as he possesses several traits hinting to a certain immaturity. He wears two slim, sagging belts at the top of wide-legged pants. In the animated adaptation, his jacket has white piping. His right shoulder has '億' ('Oku', the kanji for 100,000,000) printed in large, light letters between his shoulder and elbow, mirroring the word 'BILLION' on his left. He also has a larger dollar sign on the middle of his chest. He wears a dark, modified Japanese school uniform, featuring a double-breasted jacket, which he decorates with metallic, golden emblems, including a yen (¥) sign on the right of his collar and a dollar ($) sign on his left (more accurately, a cifrão with two vertical lines). In his initial appearance, his hair's temporal points have pin-like objects in them and the back has notably more spikes. He sports a small, dark pompadour with the sides lighter in color and two spiked rattails in the back. Two fine lines cross his face in semicircles passing the inner corners of his eyes. Okuyasu is a young man of above-average height and medium to athletic build.

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