I’m currently searching for this doujinshi called シアワセキス by Satsuki Yuu (沙月ゆう) from the series Kamigami no Asobi – Ludere deorum (神々の悪戯). The circle its part of is あわいろ. The main characters in it are Laevatein Loki and Kusanagi Yui. Release date: 2014-6-29 and it has 20 pages.
I tried to find it on auctions and on some other sites, but it was listed only in Suruga-ya:
Two shopping options there, through Suruga-ya itself or through an integrated store via the marketplace. But both are out of stock at the moment :/
I added both to the alert list. When they notify me, I will send you an email letting you know! 🙂