Whooo. A lot to think about! Lemme break it down.
Purpose: The fluff text is mostly just that — it's my IC reasoning as to why anyone would want to create the Chiaki-class to begin with. That reasoning can change depending on what else is out there. At the time this was started, no one was talking about the Arashi being replaced.
Now we apparently are talking about that.
If the Hayai is destined for approval, and that seems likely, then it really does fill the Ketsueki's roll much better than the Chiaki. It has torpedoes, after all, which can bring major damage in a short timespan. It also replaces the Yuuko by virtue of size, speed and capabilities.
That means the Chiaki is not filling those roles.
However, the Chiaki doesn't have even half the weaponry of the Arashi, never mind the damage potential. If I were Yamatai, I'd be refurbishing my Arashis (and thus giving them new art) until they were up to snuff. Then I'd build more, minus the big Legacy cannon. Sure, the Chiaki (as it stands) has 20/20 (2) damage resistance, but it has very little in the way of damage potential compared to the Arashi.
Chiaki =/= Arashi, in other words. Is it meant to fill that role just because it's convenient? I can always make up stuff in the fluff; I just need to know if that's the case or not.
Is it a gunboat or escort or what?: I gave the Chiaki the bit about "wolfpacking" because alone, they are much less capable of quickly dispatching an enemy vessel, which I felt was a necessary component of fleet defense.
In a pinch, they CAN fill in as an offensive unit, and be fairly effective. It's just not their designed-for mission of capital ship and/or fleet defense. I'm not trying to step on the Hayai with that point; Nash's ship is smaller and has better offensive "moves" than the Chiaki.
More than anything, that "wolfpack" part is just me. I want my designs to be utilitarian and versatile, capable of filling in (but not necessarily excelling) wherever they are needed — just like me.
If that part offends, I can take it out.
Deadly by design: I was going back and forth about escape pods or a Soul Savior Pod. I know I wanted one or the other.
I think I went with escapes because people had called the SSP lame and thought it reinforced the "durr hurr Yamatai never dies" motif of the Star Army. But honestly, it's a small, cramped ship that uses as much of its space as possible. It probably should just have an SSP and send everyone to the shuttle bay in an emergency. Last one there gets revived in a Yui clone!
On the hull: I realize now my math was wrong and I put in the wrong hull number. According to the correct math, I have enough SP (Size 1) left over to give it a 16/20 (2) damage rating, so I'll stick that in instead.
A hull of 8 makes it the most flimsy starship Yamatai offers and pegs it in a civilian class. The Chiaki is supposed to be tough as nails, and a hull of 16 makes it that without encroaching on other ships.