'Now...'
Song Lei left the class and decided to wait till the night. This sounded like a crazy plan, but it was better than going back to his house. There were several reasons for this. The first and most important reason was the fact that there was a monster in loose back in the apartment. Song Lei didn't know where it had gone after he had let it run away.
This created a huge problem of uncertainty. The monster could even be hiding in his room, waiting for him to completely drop his guard. Or it could be laying in wait in the next room. Song Lei would have no way to know where it was and he wouldn't have the ability to get ready for it.