This chapter made me realise that the princess wasn't as young as I had thought...
The demons thought she was in kindergarten, and while I somewhat agree, I wouldn't be surprised if she was a few years older, 13 being the oldest. But I certainly did not expect a young adult.
Edit: I should've realised sooner. A-something-kun was a childhood friend of the princess. A hero, logically, wouldn't be a kindergartener.