Sakuya-san O Sukikatte Ni Dekiru Ken [English], an hentai doujinshi parodying the Touhou series, by Marugoshi (circle 54burger)
In this share, a young human male accidentally winds up in the youkai world and is hired into the scarlet devil mansion, called here the Koumakan, I didn’t know the Japanese term before. He falls in love with Sakuya (the head maid, braids, tsundere, soft M), and on a whim the manor’s master, Remilia Scarlet, invites him to their night games. Long story short, he’s allowed to do whatever he wants to Sakuya, under Remilia’s appreciative gaze =)
The drawings are pretty good I found, for a doujinshi, they were good for a fap, and perhaps more than that, for the sheer reading pleasure
But I must warn you, the ending is SUPER unfair
It’s been released by Desudesu and commissioned by a kind anon, thank you!
By the same artist, I also share Kin Kore.
And now, the download & gallery links 
Open the Complete Pictures Gallery
Download the Free Hentai Manga in a Zip file
(32 MB, 25 pictures, English)
Or you can also use the Alternative:
Zip Mirror #1 – or – Zip Mirror #2 – or – Zip Mirror #3
Page 22 – Male protag-kun’s hopes and dreams went up in smoke, there ….. and Sakuya-san was hot, too.

That’s funny, I thought the ending was going to be of a nutritious variety.
C
For the record, the title of the KanColle doujinshi is… well, the “Kore” part is technically correct since that’s how “Colle” (short for “Collection”) is pronounced in Japanese, but the first part is ambiguous, since it’s written in KANJI. The character in question can be equally read as “kin” or “kon”; without furigana, we cannot tell which one it should be. That being said, the translator rendered it as “Kon” in the actual doujinshi, while for some reason it was replaced with “Kin” when it was uploaded to E-Hentai; other sites that host this doujinshi seem to go with “Kon”, though.