She should be the next UR in this event. Not a hater on Vanguard but I don't want another UR BB. The big 3 is enough.
Unfortunately, Manjuu has kind of backed themselves into a corner when it comes to damage dealers. Battleships are just far better boss killers than Carriers right now, largely because Battleships generally don't require a whole lot of special set-up like slows. With how accurate BBs are compared to torpedoes, we're pretty unlikely to ever see Carrier boss fleets take center stage. Sakura is the only faction that comes close, except they can't ever use Nagato because they need a slow providing main fleet ship.