Now I'm starting to see the rationale for this lineup: the obvious three aside, Tenryuu has excellent CQC abilities and Akebono is the best shooter in the base according to character profiles.
This is Final Defense Line, seconds before the target reaches the operation area: ...4,...10cm Twin High-Angle Gun, armor-piercing sniper variant Mk.2, was it? I see how the Navy can't use this kind of thing.