Shinnōke

Seshū Shinnōke (世襲親王家) was the collective name for the four cadet branches of the Imperial family of Japan, which were until 1947 entitled to provide a successor to the Chrysanthemum throne if the main line failed to produce an heir.

The heads of these royal houses held the title of imperial prince (親王, shinnō), regardless of their genealogical distance from the reigning Emperor, as the term seshū in their designation meant that they were eligible for succession.

In the Muromachi period, Prince Yoshihito, the son of the Northern Emperor Sukō was permitted to establish a parallel lineage to the main imperial line, and took the name Fushimi-no-miya from the location of his palace.

This served politically to cement the reunification of the Northern and Southern Court, but provided insurance in the extreme event that the main imperial line should fail to produce a direct heir and become extinct.

Non-heir sons who entered the priesthood were styled princely priest (法親王, hōshinnō), and were automatically excluded from the succession, but could be recalled to "secular" status (and thus reinstated as potential successors) if the need arose.