My sister is a magical girl!

My sister, with whom I've had a long-standing feud, is actually a magical girl? Wait, isn't it said that sharing secrets will improve our relationship?
That statement is a complete lie, isn't it?
Why do I still feel stung by those cold stares?
Sister: "Don't get involved, things will get... really complicated."
Chen Yu: "......"
An everyday life that is not typical of everyday life, unfolding.