Experienced a hardlock when trying to do the quest for the Teddy Bear Student in the academy. I am assuming that nightshade only spawns at night in the academy grounds. In my game, if I attempt to exit the main building into the courtyard during the "evening" segment of the day the game hardlocks.
RPG maker does NOT stop responding, the game simply stops and accepts no inputs other than console commands i.e. the F keys.
If a save file will help you, i can send it to you.