Still no explanation of what determines suit compatibility, huh...
This whole situation's a bit surreal, honestly. It's like if a scrawny 8-year-old joined the special ops because they passed a field test by secretly teleporting to the goal before anyone else. How exactly are they going to prove themselves in the special ops if they lack everything that's expected of them, and can only offer what no one expects and no one can know about but which somehow achieves results?
The only answer I can come up with for Kafka to prove himself is that he'll somehow raise his suit compatibility via his "kaijin factor" or equip a fake/hacked suit that just utilizes his kaijin strength and pretends it's the suit... but more likely, he'll just be thrown into combat and repeatedly mysteriously achieve incredible results. For example, maybe he'll just stay a cadet who's supposed to remain in a support role, yet repeatedly wander onto the battlefield, and then eventually some higher-up will see him standing next to a kaijin's corpse and just arbitrarily promote him. Maybe his suspicious new superior will even uncover his secret and officially recognize him, making him a support cadet who's sent on secret missions to beat tough kaijin.
For the setting's integrity, I'd rather he at least tried to fight the way a troop member fights. That should be what it means to "fight beside Mina". That, or she'd have to learn his secret so he can fight beside her as a kaijin...
Anyway, the twintailed Kikoru is probably my favorite character right now. I kinda want her to hang around Kafka and make Mina jealous.