Never used one of these nibs. Are they so special in writing (not in looking at)?
I own two – a Naginata Concord (NK), and a Naginata Concord Emperor (NKE) – but have only used the former of those so far; the latter is still in a pen that is factory-sealed in a plastic sleeve. It's certainly well-made, and an interesting nib with which to write; and, yes, it is special in the sense the user can get different writing outcomes from it. That doesn't necessarily mean that one couldn't get similar results from, say, a Sailor Zoom nib, or a custom/architect's grind, etc. depending on what the user actually wants.
Some of my writing samples with:
• Naginata Concord nib: here, here and here
• Sailor Zoom nib: here and here
The range of line widths with brush-like strokes that one can get out of the Naginata Concord nib is wider than that from a Zoom nib. On the other hand, for cursive writing in English, I think a user is more likely to get the desired manner of line variation.
Sailor has some cheap pen models with Fude de Mannen nibs (which is essentially an upside-down Concord nib, but I find the design of the Concord nib more suitable for my purposes), and there are also Naginata Fude de Mannen nibs, but of course the build quality in the cheaper ones are not nearly in the same league; that I can tell you from first-hand experience. I also have a Duke pen with a Fude nib, and it doesn't even write properly upside-down to lay down a fine line consistently.
I don't know about Naginata Togi nibs, as I don't have one and never used one.
As always: 1. Implicit in everything and every instance I write on FPN is the invitation for you to judge me as a peer in the community. I think it's only due respect to take each other's written word in online discussion seriously and apply critical judgment. 2. I do not presume to judge for you what is right, correct or valid. If I make a claim, or refute a statement in a thread, and link to references and other information in support, I beseech you to review and consider those, and judge for yourself. I may be wrong. My position or say-so carries no more weight than anyone else's here, and external parties can speak for themselves with what they have published. 3. I endeavour to be frank and truthful in what I write, show or otherwise present when I relate my first-hand experiences that are not independently verifiable. If it is something you can test for yourself and see the results, I entreat you to do so.