[Samozumo Tooru(さもずも融)] 7 [sév(ə)n] - Chapter 01 [2014-02-27][TG-BE]
From:
Comic X-EROS (コミック ゼロス) - Vol.16 [2014-02-27]
Code:
https://www.sendspace.com/file/aewf6i
A three chapter story, according to the magazine index the title is simply 7.
There isn't a direct focus on the BE, but it's substantial.