From the same collection that I recently listed swords from, I have a high-quality early Satsuma blade with Tokubetsu Hozon kanteisho to Ko-Naminohira. This attribution ranges from Kamakura period to Nanbokucho, but possibly as early as Heian. After having studied further I would lean more towards the earlier end of that range, perhaps late Kamakura jidai. The hamon has a lot of fine hataraki like kinsuji and small ashi. The hamon is very Yamato-like and greatly resembles Ko-Senjuin. The blade is a naginatanaoshi katana, with a great shape that appears ubu, or mostly ubu, on the upper portion (while the nakago is o-suriage mumei). In shirasaya with silver foil habaki and current NBTHK Tokubetsu Hozon kanteisho.