About the
Naginata-class:
I think it'd be sensible to poke
@Khasidel about this, since it's his creation in the first place.
Also, I'd like to point out that, as envisioned, the Naginata doesn't have anywhere near the expected fleet presence/role an Irim has. It's a battlecruiser; arguably more massive and powerful than the Super-Eikan heavy cruiser. In effect, the only reason why it isn't called a battleship is because it shed weight (i.e.: armor and other protections) in favor of mounting better engines for interception roles.
Remember how the Irim-class heavy gunship was a heavy brawler in comparison to the far-ranging Sakura-class light gunship being an 'interceptor'? It's kind of the same difference the Sharie has with the Naginata.
The
Izanagi-class Dreadnought:
Another design I know Khasidel worked on was the dreadnought-y
Izanagi. It has art, it looks amazing, and already has an outline article for it. However, I think it's important to grasp the sheer
size of it. It's 22km long. It's far larger than the dreaded SMX
Shlarvasseroth ever was. It can not only contruct ships, but also create Star Fortresses. By itself, it's slightly larger than the Super Zodiac star fortress. It's probably better considered a mobile star fort, or...
The Star Army of Yamatai's
flagship role:
We have the Super Eikan, the prospective Naginata and the Sharie whom all have very high-tier artwork given to them. In contrast, we have the Yamatai-class, which still goes by with DOGA art. Another point in the Yamatai-class' disfavor is how there's actually very little reason to field it as a Sharie-class; the Sharie-class already has such a good presence on the battlefield that the Yamatai-class' status as flagship pales in comparison. Essentially, I kind of think the Yamatai-class is superfluous since the Sharie can effectively take over the same role.
If you want a flagship that stands out... I think it ought to be like the Izanagi Dreadnought. It ought to be a ship with enough presence so that no other can really match or replace it. It ought to be so important that it ought to be considered singular in a fleet... or perhaps singular in multiple fleets/regions (i.e.: the U.S.S. Enterprise was Starfleet's flagship... and Starfleet had multiple fleets). Like, if Yamatai fielded it, it could have one for Central Yamatai dedicated to serving 'Standard Fleets' and based in the Ketsurui Military Sector meant to support Expeditionary Fleets (for which it actually looks uniquely suited for).
Irim replacement?
I don't think this is necessary right now. The Plumeria-class' refit pushed it very close to filling the same niche, with the caveat of not really being a torpedo-using warship. I think that, in the aftermath of the 2nd Mishhu war, not going for a line torpedo boat like the Irim was previously makes sense, and that's why the Plumeria would be favored for filling in that niche in a more economical fashion. The Plumeria is supplemented with the Chiaki gunboat, which for system defense fills nearly as well role a Plumeria could've held, and more economically (it has no fold drive) - paired with a ship capable of folding, the Chiaki makes a great escort vessel. If you need something heavier to fill in numbers in ways the Chiaki cannot, the Urufu light cruiser more or less can do similar things the Irim could (though it's more effete/elegant and less of the fearsome beast the Irim felt like).
My Himiko Refit (which is still coming; I take my time because I still have time before I need to use it) would more or less fill the 30-35 SP category left behind by the Eikan and Irim, but I don't expect it'll really end up being used by the Star Army as a line warship when it's more of a long-range self-reliant exploration/ambassadorial vessel who'se best use is as a squadron command vessel on occasion. I view it more as a limited production ship that's seen by the Star Army as having the utility around the Tansaku-science ship, the Type 30 Space Yacht, combined with the uniquely plotship-like feel people have associated with the Sakura/Plumeria - and in a way where the ship is capable enough to not land itself in situation where it bites more than it can chew (something to which the light gunships are very prone to, and typically survive mostly due to plot armor). There are not many plotships in SARP, so, I don't expect a great many Himiko Refits.