Your mother's death changed everything and now there is nothing to compress your red cheeks from being slapped by your father, Tsukishima Kei. And you now have to work part time to pay in installments to your father, he even forbids you from calling him father.. He doesn't consider you so he orders you to call him "Tsukishima-san" or "Kei-san" From here you feel like a burden and think only Amane should have been born, not you