Sakichi has green hair which is in a bun. He has white skin and green eyes matching his hair.
Sakichi is a very serious person. He is very loyal to his master, Hashiba Hideyoshi. He is very confidant in his abilities. Sakichi showed traits of being a highly determined person, and was willing to wait as long as it was necessary to acomplish his mission given to him by his master.
He's very blunt and direct, and usually says what he is thinking without fear. Sakichi is somewhat reckless; this is shown at least once, in the first chapter when he decided to engage battle without even riding a horse, joining the combat by foot. It was observed by some characters that he is an idealist (and Okuni even described him as being a "inexperienced" one); one of his beliefs it that the people who change the world are "heroes".
He doesn't appear to believe in superstitions, as he claimed in the first Rengoku chapter that the belief that twins bring disaster was "fool". Although he is a warrior - and a very capable one -, he believes in diplomacy as a way to solve problems. One example of that was in the first chapter, when the villagers of Oumi were vandalizing the twins' temple and he tried to make they talk instead of fight.
Sakichi showed himself many times being a very honorable person; he is fully willing to protect the ones he believes that needs protection and will attack anyone who tries to harm others with no legitimate reason. Again, this is made obvious when he defended the twins' temple against the villagers.