Ore to Kanojo no Battle wa Living de

Ore to Kanojo no Battle wa Living de (とのバトルはリビングで) is a light novel series written by Hizuki Nagi and illustrated by Mishima Kurone.

Plot
Kurahashi Kazuki is a normal high-schooler, up until Leahna Irum "Leah" Luaria, a self-proclaimed demon princess, appears in his living room. Claiming Kazuki as a descendant of a hero and that she need to "keep an eye on him", Leah moves into living with him all the while hiding her feelings for her host.