It's based on the game "Kouen Itazura Simulator ver. MAKO" and drawn by the same person who made it, misooden. It's full length is 40 pages and it was released on Dec 12, 2016. Unfortunately no one has scanned it.
There is the twitter page of misoden: https://twitter.com/kodomo_h_com
And...
Thanks for replying. Can you take a picture of all the pages please? No else has posted the doujin and it's not being sold anymore so if you could do it, it would be greatly appreciated.
Full title name: タイトル:ママタマ番外編
Author: Marumiya, Uno Makoto
So I came across an extra chapter of Uno Makoto's Mama Tama series from 2012 and I can't find it anywhere! Apparently this extra chapter is 4 pages long.
This is where I found it...