A truly rare style koshirae with kamon of the Hosokawa clan and Imperial family (that they carried in Edo period). This Karabe-Uma koshirae was known for court appearance most likely as it was very glamorous to wear. If you look carefully snd interesting point is the lacquered dragon on the sheath, it is partially covering the Hosokawa kamon, as if it protects the family’s lineage. Also the lacquered Phoenix matches that of the Phoenix found on the kozuka and Kashira.
Norikazu was also known as Hitachi Norikatsu, he signed his name Norikazu in his earlier life.