There's some discussion here:

The short version: Kairyu missiles have homing fragmentation, which gives them significant burst damage when used by the AI vs. the player. There is at least one storyline mission that requires fighting multiple ships armed with Kairyus; short of planet cheese to drain the enemy ships' ammo stores, or spamming lots of high-level repair kits, I don't see how players can plausibly handle that mission.

george moromisato 11 May 2021:

I've made a couple of adjustments in 1.9 Beta 4:

  • I've reduced Kairyu missile damage (from 2d12 to 1d12+1).
  • I've changed the tables so that ships only get Kairyu missiles at higher levels (previously, an Akuma could get Kairyu missiles at level 4 or 5).

Thank you!