What's her occupation? It says student on the Liar Game wiki, but I don't think she had any occupation mentioned in the Liar Game drama. What is she studying? How does she have the time to do all this Liar Game stuff while she is studying/working? Sick leave?
To some degree, Nao's ability to keep up with school is handwaved: other than in chapter 139, what we see of her daily life (other than the segment in the ch. 1 excerpted in the other answer) consists of her visits to her father, and we also do not see much of it anyway. However, I think we have reason to believe that Nao has not had to abandon her studies because of the Liar Game:
In chapter 139, we see her in lecture, and her classmate remarks that she's changed lately after Nao comments on a professor's appearance. To me, the classmate's observation that Nao has changed lately, rather than that Nao has suddenly changed after coming to back to lecture after a long absence, best fits in with the scenario where Nao has been regularly attending class.
So far, the Liar Game rounds do not actually appear to take up that much time, and presumably are spaced out somewhat. If so, it would not be inconceivable that Nao would have been able to go to class regularly even while in the Liar Game.
The first round takes place over the span of a month, but unlike with the other rounds, there is no set schedule for when players have to act; players would have more flexibility with the timing of their actions. (For instance, players did not have to show up to a game location at a certain time.) Moreover, although, Nao initially coops herself up at home, she is later able to carry on with her daily life: when she and Akiyama take shifts to watch her teacher (ch. 3), Akiyama takes the day shift.
The second round takes place over three days.
The first revival round is thirteen hours long.
The third round is on a "Saturday the week after next" (per ch. 29) and takes place over a single day.
The second revival round takes place on a single day.
The fourth round takes up two days. (The players go into the mansion at night to rest.)
The third revival round takes place over a single day. (It should only last a few hours.)
The final round takes place over a single day. (There is never any mention of giving the players a break for the night.)