At normal times, hostile magic beasts that are not trapped inside the resource points or are captured by humans living in the City of Hope will only appear inside the city if the city is attacked by them
However, the city was clearly not attacked considering the manner in which this magic beast appeared. If it was a magic beast attack, they should come from the city walls first before they can even have the chance to reach the Tryst Academy
Despite the fact that the Tryst Academy is located inside the outer walls of the City of Hope, as a reputation academy, its location was definitely not on the outskirts of the outer walls. It was situated near the inner walls. As such, even if the magic beasts started a full-powered assault, it would take time before they reach the Academy and that would surely cause a commotion. It is impossible for them to appear in such a manner