4/23 is Book (Motoori Kosuzu's) Day! A human who lives in the Suzunaan book rental shop in the Human Village. She can read all sorts of texts.

This book is quite thin! Doujinshi, usually ones that have adult content, are often called thin books (usui hon) in Japanese, owing to their self-published nature leading to them having few pages.

Is that true?! This book is written in the language of the youkai?

I'll hurry home and study it at once!

Kosuzu-chan's face was bright red as she deciphered the book at home.