@loodySorcerer
In Japan, if you are Hiighschoooler and want to work part-time, the requirement is permission both from shool and parents, Neko hime sensei that the school doesn't really prohibit a student from working, and with Segawa, parents said OK, now it is save for Segawa to work.
I am also confused by the power supply/battery thing,
by its name, it is not really wrong to says battery use is to supply power, but the technical principle behind how those two things works are different, battery like in notebook is to store electricity while power supply in OC is to convert AC to DC