I found also this one which is papered but also with a kikumon (I don't own this book : Showa token mei mono Chiyo). This doesn't prevent this sword from being gimei, especially when you look at the quality of the engraving.
https://www.nipponto...swords3/NT327636.htm
Never seen a Yokoyama Sukenaga with a tachi mei, and at this time he inscribed kikumon ichi on his nakago
https://www.touken-s...2/K-sukenaga-01.html
https://www.sanmei.c...31085_S5216_PUP.html
It means suguha is mixed in (with) notare .
I didn't say the hataraki weren't important. I said they could be overlooked because I haven't yet tackled the subject, which for the moment is the shape of the hamon.
This one should be easy to find.
3 波平安元 Naminohira Yasumoto are recorded in the Nihonto meikan one Koto (OEI) and two Shinto (Kyoho, Tenmei) Due to the nakago shape, Oei is a possibility.