You will need 2 Honda parts:
The rack is part number: 08R71-MJS-A90
And you will also need the replacement plastic cowl piece that allows the new rack to mount and that part number is: 08R00-MJS-J70ZA
Not sure where HondaFriend ordered his from, but this is one of the most popular Japanese parts sources. They are reliable and ship very quickly. Prices are pretty good too.
My only reservation is this:
Honda has not published any load specification for these parts that I can find. Notoriously, you find that the parts are not designed for much more than a jacket or maybe a helmet's weight. This isn't to say that the rack won't hold more, only that Honda won't back anything heavier if damage occurs.
USA OEM MSRP for the two pieces are: $450 (rack) and $100 (cowl) and it isn't too hard to find places charging more than MSRP.
These are the photos off the US Honda website:
If using the passenger seat is a high priority, or if you have no means to build your own rack, then this might be your best option. However, for my use, I found this option unattractive for the following reasons:
1) Cost - holy crap, $650 for a rack? The metal and paint for my solution was about $15 and took about 30 minutes of welding work.
2) Unknown weight capacity. This really is important because if Honda only recommends 5 pounds then this isn't really a great solution.
3) Holds the topcase way off the back. Practically the entire weight of the topcase sits behind the taillight. More stress on the mount as the back end moves up and down.
4) There is an upward bend to the rack at the rear. Perhaps this does not cause an issue with HondaFriend's tocase, but mine would not have fit flat with that bend there and it may not be an easy matter to flatten it.
5) The design does not seem to have any cross bracing. As you carve corners with any weight on the rack, there will be side loads applied. I worry about how those weight shifts will cause sway in the rack, and what kind of stress that will place on the upper and lower mounts. The upper ones can be checked easily enough, but the lower ones are hidden by the rubber on the cowl.
The installation is pretty straight forward on this piece. The factory rear cowl comes off easy enough with the tools in your factory tool kit. (don't forget the hidden 2 pin clips under the fender) Then you bolt the two supports to the threaded holes on the NM4 frame. Install the new Rear Cowl with the rubber guides. Finish assembling the upper section of the rack and backrest. Attach topcase of choice.
I'm very torn by this design.
On the one hand, it is a simple and elegant solution that keeps all the NM4's features intact. On the other hand, so many unknowns and a rather questionable design raises concerns on capacity.
I realize that my solution is extreme overkill in that I not only used material that is far larger than required, but I also braced the main point of stress such that it is likely stronger than the frame on which it is attached. I'm not trying to compare my solution with the factory part, but rather questioning the strength of the factory part for real world use - that is, loading up a topcase with all the stuff you need to tour regardless of the weight. I know for a fact that over the years, I've put significant weight in my topcase and while you need to manage that while riding, you should not have to worry about the mount failing too. Lets face it, if the bike was designed for a passenger, then the back end should not have a prohibitive weight concern. I just like to reflect that in the cargo as well.
For the record, here is my solution again: