has a very delicate character. He hangs in a very fine and sensitive balance that can tip either way to the least of stimuli, be it an incident or another person. His foray into hooliganism, repeated loss and sudden surges of confidence are all part of the seesawing of this balance. 
            He harbours a deep sense of bitterness which we get several glimpses of. He regrets his loss of two years and feels guilty of letting down Anzai Mitsuyoshi whom he respects. This bitterness manifests itself as the diminishing of his cocky zest when he fails. 
            Although the above two characteristics are the most outstanding in Mitsui, they are usually not noticed. The most noticeable are his hot-temper, violent streak and proud exterior. He is not an expressive fellow. But he is not one who take things lying either. He possesses a strong sense of rivalry. Anger is his most expressed emotion; the scowl is his trademark. 
            One interesting point to note is his dislike of praises and flatteries, especially loud ones, by people he knows. He used to be quite a show-off. 
            Mitsui did very badly in school. He is neither stupid nor slow. In fact, he has an agile mind. His poor grades seem to have more to do with his laziness. 
            Perhaps it is all that he had been through or maybe it is the lack of competitors, Mitsui gives one a feeling that he is old and mature. His character is one of the rare ones we see such drastic changes or should I say developments and such complexity.