With all the power struggle/backstabbing going on, it's no wonder that girl is pretending to be a guy for some reason and I guess she's using a fake name as well, otherwise MC would've remembered her/him from his previous life.
To anyone wondering if the new girl in this chapter is a new Harem member or not.
No, she isn't yet, atleast per the recent WN Raws (though she probably might eventually be one, as
MC did come across her later while her clothes were soaking wet with her sweat because of training
, then her reason for hiding her truth is related to something else. One being easier to move around as a guy, than a girl. And the other being her case is somewhat similar to MC but reverse, aka.,
she is someone from the past who as a baby got sent into the future, and the one who sent her were her parents who were defeated by that Sage Emperor guy
Only problem I have with these are that I have no knowledge in asian names so I almost never remember any single one of these names and it ends up sounding like gibberish when they're naming a ton of different things at once.