Board Thread:Fleet's Prepared-ness/@comment-27197385-20180203130539/@comment-32647310-20180203141122

Aircraft, plain and simple. You also need more M21s and M52s as development material (more on that in a moment)

Fighters that are improved via Akashi are +2 to their Anti-Air/Air Power at +10 (for example, your M53 (Iwamoto) would be treated as a 14AA fighter)

There are also effiecent and effective ways to make the most of Akashi and your materials by following certain quest-chains;

If you use a quest-chain to improve a fighter to the next level (such as F25 where a M21 becomes an M52), the improvements carry over. Therefor, a +10 M21 that's used in this quest will become a +10 M52...the most powerful carrier fighter that one can acquire on a semi-regular basis.

This said, if you do the montly F22 quest (you will need Skilled Crewmembers for this, so I suggest you get yourself some M21 fighters to +10, so that when you're able to do the quest, you will have a +10 M21 to start with. The reward will turn that +10 M21 into a +10 M21 (Skilled), which is then used for F24/25 (same quest; turns an M21 (Skilled into an M52 (Skilled, it's just F25 is a monthly repeatable).

Red Planes are kind of in the same boat. Even though there aren't any quests that let you upgrade a plane from a low-powered version to a higher powered version except for the M62 (Iwai) (to the best of my knowledge anyway), you can upgrade the M62 (fighter-bomber), M63 (fighter-bomber) and M62 (Iwai) through Akashi as well. The result is similar in that it's a +2.5 to Anti-Air/Air Power (at +10, the M62 (Iwai) is treated as a 9.5AA fighter-bomber).

I would say you may also want to get at least one more Seaplane Fighter; You have 3 at present, and I've heard noise that having 4 is optimal.

Hope this helps!