User blog comment:Godisme/Everything But The Rain Op. 2 "The Rudiments"/@comment-2120712-20130306154115

Maybe he caught the hollowfication virus or whatever Aizen is using to spread it and in order for Isshin to be cured, Urahara put him in a gigai that cures him but it takes decades to d so fully with the side effect that he loses his powers while inside it and in order to be fully cured has to stay in the gigai at all times. He is currently cured, but he stays inside the gigai since he has a family and probably prefers the human world to the SS. So he was a head of a branch of the shiba clan or was he the head of the clan in its entirety? That part confuses me.