I love how this is effectively a story about teenager anxieties, and the absurd supernatural shenanigans are mostly a way to channel them. Sanda keeps falling in the usual pitfalls of teenager stuff (in this case, making his own life harder for himself by revealing a weird secret), but because he did so in an earnest way, because he was trying to make the other descendants (exchange students) feel more at ease and to let them know they are not alone, he is getting a literal powerup.
Santa gives gifts to good children, in the end.