Thank you for playing and for pointing out the crashing bug when re-entering the classroom where the game intro begins. I've fixed that crash along with a few other minor issues and will upload a new build after the judging period ends. Can you give more details on the missing character sprites or post a screenshot of the issue?
This jam entry was created with C# and the Monogame framework without using a commercial engine by mashing up the JRPG combat system from Robot Magic with the 1st person dungeon crawling view from Ponsona(which was also based on Robot Magic)