Evil Spirit Possession

Story
"""Reimaden,"" huh? Stray pages of tattered books, papers that look like official documents, symbols carved into structures made of stone and metal, floating summoning circles that were surely crafted by some form of magic, and strange symbols made solely of light... I compared them all and was finally able to make out a word... ""Reimaden."" It doesn't look like I'll be able to return home anytime soon. Hey, little phantom, do you mind giving me a hand?"

What's a... "battle of bullets"? I feel like I've read about this in some other world. Taken at face value, a battle of bullets just sounds like a big brawl where people fire endless bullets at each other. It seems like the evil spirit who lived here spent some time practicing her aim...

"This part says... ""I'll exact my revenge on all humanity""! This evil spirit sure dreams big. It'd be pretty scary if she was serious, though. I heard there were evil spirits and vengeful spirits in the past who plunged whole nations into chaos. Maybe this evil spirit was one of them. ...Huh? She says she's giving up on her plans for revenge on the very next page!"

"The ""power of Yin-Yang... somethings."" Looks like the evil spirit was after the power of these Yin-Yang items. Lemme see here. They can only be wielded by... a shrine maiden from a specific bloodline. ...Ah, I see. Without the shrine maiden, the evil spirit can't use the power of the Yin-Yang things. And without that power, she can't exact her revenge on humanity. Which is why she needs to ""have a spectacular battle with the shrine maiden."" Regardless of their original difference in strength, the Yin-Yang items make it an even fight... They sure sound incredible."

"""The evil spirit and the shrine maiden."" I see, I see... Based on everything I've deciphered so far, it seems the evil spirit and the shrine maiden were battling, but got distracted by how much they were enjoying themselves! So basically, they were risking their lives for a bit of fun... We really are from different worlds. You think they're crazy too, right, little phantom? ...Hey, where are you going?"