I Just Came Back from Rebirth, Why Did My Junior Sister Become the Demon Emperor?

[Contrast and cold junior sister] [Sweet and sadistic] [Not brainless] The junior junior sister Mu Qingyan, whose identity is a mystery, will become the powerful empress of the demon clan in the three realms in the future. Mu Jianghuai, as her senior brother, traveled back to before everything happened, but discovered countless details that had been missed. Mu Qingyan's darkening was not accidental at all.