Nice cover, indeed.
And from one of the best arcs in Usagi, in my opinion.
The only drawback for me is the lack of background, but I would probably go for it if I had the money.
As for your question about framing and preserving art:
I put most of my art in pressbook portfolios like this one (this is the best among those I have):
http://www.prat-usa.com/mera-presentation-case.html
However, this brand seems to be much more expensive in the US than it is in Europe, so I if you are planning to buy a portfolio, I suggest you find the equivalent model in another brand. (I've heard plenty of american collectors talking about the Itoya brand, so I think it may be worth a look)
For those I framed (not many, since I don't have many empty walls), I always ask a professional to frame them for me using non-acid products (very important for the conservation on the paper) and anti-UV museum quality glass (for preventing the paper becoming yellow with sunlight).
If you are planning on framing them yourself, be sure to use non-acid paper for mats, both in front and behind the art. The mat behind serves to absorb acidity that could eventually come from the wood or material in the back of the frame, and the mat in front is there so the art is not in direct contact with the glass.
As for the anti-UV glass,it's here to reduce damage from sunlight, but it's not a magical solution that will keep your art perfectly safe.
So, here are some additional recommendations, even if you choose anti-UV glass like me:
Never put your frames in a place where they will be in direct contact with sunlight. Always pick a room with low sunlight, and a wall with no direct exposure.
Even with low exposure to light, the ink in the art will fade. The lower the light exposure, the longer it will take, but there is no way to completely cancel the effect, unless you want to store your art in portfolios and never look at them (which would be an efficient way to preserve it, but a bit sad).
An interesting read on the topic here:
http://boards.collectors-society.com/ub ... ost8846510
So even if you display them, my advice would be to limit the time they spend on the wall. If you have several pieces framed, it could be a good idea to rotate the pieces on your walls (a piece on the wall for 3 months, then you put it in storage away from light, and pick another piece of art to display), so no piece gets too much exposure.
I have to say that in this matter, I am a bit extreme (and you probably don't want to go as far as I do

), as I only put my framed art on the wall when I organize a dinner at my place, after sunset. So they only get exposed a few hours per month, and only in artificial light. (I told you I was a bit extreme.

)
The rest of the time, the frames are covered so not to be exposed to light. I still flip through them and uncover them when I want to admire my art, though (what's the point of owning art if you never admire it

), but I don't feel the need to see them everyday on my wall.
A few additional points, but far less important than light exposure:
The ideal humidity level for paper conservation is between 30 and 55%, and it seems most museums keep their paintings around 50% humidity level. So, I guess for comic art you can safely assume that above 55% your air is probably too humid, and too dry under 30%.
I have a small device to measure both humidity and temperature (it cost me around 30$) and have a dehumidifier (a couple hundred bucks) so I can try to stay between 40 and 55%. It's probably obvious, but it's probably best to avoid hanging art in humid rooms like bathroom or kitchen.
As for the temperature, ideally, it should stay low (let's say, around 18-20°C), but I don't have AC, so there is not much I can do about it. It doesn't seem to be the most important factor in conservation of art anyway.
For humidity and temperature, it seems the most important thing is to avoid sudden variations (so it's probably not a good idea to put your art in the fridge during a hot day, as the sudden drop in temperature could damage the art more than the high temperature. No, I never tried, it's just an example

).
Here are the general guidelines. Now, it's just a matter of compromise, as keeping the art completely safe is impossible if you want to enjoy it.

(and even without enjoying it, I don't think "completely safe" really exists)