His swordsmith is said to have learned from Izuminokami Kaneshige, who was also said to be the teacher of Kotetsu.
Okita Souji was known as being very respectable in public: kind, sarcastic or a jokester, and someone who played with kids often. Towards his fellow comrades, however, he was known to be very strict. As such, it appears Yamatonokami took after his owner.
Believed to have been used by the Shinsengumi's Okita Souji, chosen from the fact that he is difficult to wield. As such, he is looking for someone who will love him. He might seem docile at first glance, but when he enters the battlefield you can catch a glimpse of his peculiar charm. (from official twitter)