It's pretty simple,really. I just gotta know about them, and wikipedia doesn't have a lot to offer.
In what period and capacity? There's a a fair amount about the Yamauchi/Yamanouchi family in English because the Tosa archives are really well preserved compared to many other old domains. Several scholars have used them as a basis for their research.
Are you interested in the origin of the family circa 1600 as Tosa lords or something else?