@thatno0b I don't think he is using fake identity now, I mean he reunited with his real family after all, theres no need fake identity. But, if what you mean is when he is an active personel combat, that's possible.
But, my point is the crash incident must have a report right? Where the crash happened I don't think it's a top secret information, and if it somewhere a really conflict areas that have war raging on. Then the question would be, "how can he survive in that environment?" Then we have the hint in this chapter: he is a profesional combatant. Now, they only need to bring that information together and that's it right? if they look at hindsight.
@Totallynotdom yeah I believe his info got tweaked a bit by them, after all it will become a problematic right if the info of 'there's a highschool boy who really a pro combatant and probably have an experience killing people having a normal school life'.