Study, Den, Library
noun
I write for purification. I do this purification writing in my study and den.
しょさい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
今日は一日中書斎で重要書類を探していたんですが、まだ見つからないんですよ。
I was searching for an important document in my study all day today, but haven’t found it yet.