[Seraph of the End] Guns and Roses

"...I should have died two years ago." The speaker was a young woman of lovely features and an expressionless face, tightly surrounded by the flames of a demon-curse weapon. "So I'm no longer afraid of death." ★ A Mary Sue (the heroine maxes out every skill, and trust me, there's a reason for that!) ★ The male lead is Hiiragi Shinya, with Fei Niang making an angry cameo. ★ The heroine is a little expressionless, a serious and proper person (not). ★ Loyalty is a charming trait. ★ The timeline is bizarre. Guess for yourself, hahaha. Shinya is 22, and the heroine is 20.