The enemy who all the time was laying doormat, waiting for random people wandering into the most obvious place, just to enslave them and for Shuichi to finally come, now is making a huge change in their state
Gee, wonder if they will be staying there forever or finally make a move... nah, let's just wait couple days...
Shuichi could take Claire offer and finally spend some time together, but chosen to go school, bad idea in my opinion.
If Shuichi wouldn't be at school that day, probably Kaito wouldn't massacre everyone to draw him out as it all started when he saw him.
Well, that was bizarrely shocking... Mifune seen some heavy shit...