Tetsu's over protective, easily worried and rather high-strung older brother/guardian (also an actual member of the Shinsengumi). He is polite, soft spoken, and down to earth. After the death of their parents, he had to take care of himself and his brother. He, in accordance with his more pacifist outlook, works only as a bookkeeper for the Shinsengumi. He has tried to put all thoughts of revenge for his parents' deaths out of his mind, but convincing his younger brother to do the same is a little more difficult. Tatsu has a habit of apologizing for his little brother.

Source: Wikipedia.