When I was a teenager, my mother and I would sometimes try to spook the other for fun.
I can’t remember who started it, but my mother was mad because it often happened near a dangerous area: the steps leading into the basement. The door would be closed, and someone would round the corner after reaching the top, only to find the spookster ready and waiting.
It was initially revenge on both ends. “She scared me, so I’m going to scare her back” and vice versa. But the petty revenge eventually waned and it became more of a “game” that kept us on our toes.
Nowadays, my spooking habits are over. No more revenge either. Yet Masamune-kun no Revenge reminds me of just how far some people are willing to go to exact the latter (minus the spookiness).