Uchi no Onee-chan ga Saikyou no Binbougami na no wa Mondai Darou ka? (Volume)

is the first volume of the Uchi no Onee-chan ga Saikyou no Binbougami na no wa Mondai Darou ka? light novel series, written by Kashima Usagi and Illustrated by Kayahara. It was released under the Dengeki Bunko Imprint in January 2018.

Synopsis
I'm Kamiharu Shien. At school, he is a perennial and very poor man. The reason for poverty is that Fukuno, the poor god of self-proclaimed "my sister", is possessed. Fukuno is cute, but when she gets upset, she's scared enough to leak. Seriously ... One day, I got acquainted with twin beautiful sisters, but they got caught up in a bad case ...  I don't know. Hey Fukuno, would you like to help them?

(source: Dengeki Bunko Official Website - Translated)