If it is confidential (1-3 volume is the latest issue)

Publisher: Akita Shoten
Author: Kanno Glycarchy
Size: 128mm x 182mm
Number of books: 3
Language: Japanese
Category: Youth manga, manga
Latest release date: 2018-07-20

Synopsis:
It's a human, and there are many hobbies and preferences. Some of them can't be a story.
My younger brother, Blue Sou, is such a guy. The guy who has seen her sister, Akane all the time.
I happened to find it. No way my sister is playing SM ...!?
The secret pure love story of my sister and younger brother !!