However, the shogunate also allowed his younger brother, Katō Naoyasu, to carve out a 10,000 koku portion of the estate and to establish Niiya Domain and a cadet branch of the clan.

This move was vehemently opposed by Ōzu Domain, and relations between the two branches of the clan was hostile for the next two centuries.

The noted Confucian scholar Nakae Tōju spent his early career as a retainer of the Katō.

The domain was also a sponsor of nascent kokugaku studies and expressed strong loyalty to the Imperial house, even from the early Edo Period.

Although relatively small domain, it played a large role in Bakumatsu period events.