Reborn: My Journey Begins with Slaying Demons

[Slow-burn plot + not a power trip + academy + realistic world] Demon eyes, blood-gold weapons, the World Sea, ocular arts... Mysteries and reality keep intertwining, crashing into the life of a chuunibyou teenager. One day, an armed helicopter circles overhead. The war between humans and demons, hidden in history, begins anew. What will become of humanity? This is not one person's story, but the tale of a group of people seeking redemption.