I've been looking at pictures of blades that are conformed as being made by Nagasone Kotetsu and I'm not sure that I see a bunch of differences. For example:
http://www.christies.com/lotfinder/Zoom ... 4/D5078430
http://world.choshuya.co.jp/sale/sword/0504/kotetsu/
http://www.nihonto.com.au/html/kotetsu_.html
Others that I looked at:
http://s420.photobucket.com/albums/pp28 ... 20Kotetsu/
The top character on all of these appears to be the same one and the style of writing is very close as well. The one from the Samurai Swords book is the closest of them all though and shows the same style of writing. The distinctive pointed end to the characters seems to be a characteristic of this maker. Thoughts?