@Kaiju It doesn't add anything substantial at the moment, but it will eventually become relevant (if ax doesn't come before that). Plus it does add more depth to MC: though he is similar to other isekai protagonists, mystery about his former world and him hiding this information makes him more of a character than a plot device. It's similar to Touma from Toaru series, who, despite seeming like bona-fide generic MC at the start, is much more complicated both in personality and power-wise.