I want to do some spherical lesbian in a vacuum calcs to figure out just how implausible trying to meet 150,000 people during highschool is.
So, you need to meet 5.7 people per hour. Maybe workable. It'd be like a speed dating setup or something.
Except that you need to sleep. With 16 hours a day meeting people, that's 8.5 people per hour. Still workable.
Now consider classes. I don't know exactly how much time classes, meals, etc take up, but consider at least half of the time. 17.1 people per hour, or less than four minutes a person.
Oh, and consider transit time. Given that the school doesn't look like minecraft entity cramming, it's probably massive to have enough space for all the students. That means our heroine has to spend lots of time traveling to find new girls.
And she has to worry about repeats, too, and misidentifying girls already in a relationship as single, meaning she'll have to actually meet more girls.
So definitely not. Not unless she busts out the shadow clone jutsu.