Saitou was former head of the Shinsen-gumi. After the
Tokugawa Era ended, he disappeared for a while and then
reappeared as cheif of police.

Saitou, age 35, is very lethal with his weapon, and is
probably equal or even better than Kenshin with his sword
technique. He has a wife, which suprised Misao and Kenshin.
It's hard to imagine him with a wife.

In the past, when he was in the Shinsen-gumi, he fought Kenshin,
but I think it was a draw. He still wants to fight Kenshin, but not while
there's trouble going on. He's intelligent and extremely patient.
Saitou still wants Hitokori Battousai dead.

When Saitou first appeared in the t.v. series, he attacked Sano
and tried to kill Kenshin. He became a useful alley against Shishio
Makoto. He's responsible for the death of Usui, one of the Juppon
Gatana members.