Kosanta has two older brothers, Matashige and Akugorou. Kosanta went missing in the quest, Brotherly Bonds, and his brothers were scared to think that he had been kidnapped by Oni-basami, the boss of Hosuseri Shrine. Upon being found, he explains that the letter left by himself was written as him hanging out with Oni-basami, when in fact it actually was written as "Help! I have been kidnapped!" This can be seen at his absent-minded nature due to the simplicity of him writing: I have been kidnapped" instead of "hanging out with a friend". He is still friends with Oni-basami, as he takes care of his wounds after the Oni who went to look for him, the player, beat him up.