http://www.mangago.me/read-manga/mousou_one_room/sa/4b2f18018e1257e8e1b0608d55de0250_chapter-7/pg-3/
Following~I wanna know too.
I'm too late but in case you havent found it yet lol that's an illustration of the bl novel "Captive Prince".
http://www.mangago.me/read-manga/mousou_one_room/sa/4b2f18018e1257e8e1b0608d55de0250_chapter-7/pg-3/