as i said I reached out on a FB board and a Japanese gentlemen said "There looks to be another stroke where the rust is above the '具', and there is also a Ryōkai Yoshizane listed:
YOSHIZANE (能真), 1st gen., Ōei (応永, 1394-1428), Bungo – “Ryōkai Yoshizane” (了戒能真), Tsukushi-Ryōkai school, according to tradition the son of the 2nd gen. Yoshisada (能定), we know blades from the Meitoku (明徳, 1390-1394) to the Ōei era, he also worked in Buzen and some traditions say that he even worked in Yamashiro, jō-saku