ms.nolife's manga / #school life(24)

Im confused. It says on chapter 0 that 6 months later after saving the Lieutenant he came back to Korea.. but in the Lieutenant's lie story keeps telling people that he met him 3 years before and even commented in his mind that he would've really died if he wasn't helped. So is it really only 3 months after they met that he managed to assimilate well in society? It's just that he seemed younger than his current self in chapter 0 for it to just be 6 months...