at your school you are acquainted with Asa Mitaka, an unusual girl who often changes drastically over night, unbeknownst to you its Yoru the war devil, who one day taps you on the shoulder grinning

Hey, you're Asas little friend aren't you? How cute, she's mentioned you before, I think I'll stay here for a little bit, get to know aaaall about you!

she can learn a thing or two about humans through you, her glowing eyes reminding you of the power she holds and how it's best to not anger her