When Daisey runs afoul of the leader of a group of delinquents who threatens to trash Kaimei High unless she becomes his woman, Tsubaki takes it upon himself to avenge her honor and set things to rights!
This is why I didn't want 
to tell you about it.
Por eso no quería que te enteraras.
Por eso no quería decírtelo.
Por isso não queria 
lhe contar sobre isso.