@kronix How does he know anything? From what I can gather, the MC has no memories from this world, and cannot properly use magic here yet. However, he can talk and read fluently and has general knowledge of the ways of our society. My only theory is that translation magic was part of reincarnation, and he learned everything else he needed to know from the magazines in the hospital before leaving. Else, the parallel universe he came from is way too similar to ours.
Surprised she isn't questioning him more, he has no memories, yet he is not only able to carry out this mission, but was overly useful in it(he found the hostages). He agreed with her that an expert killed them, but how would mr mindless know?