The events that happened during that one week, are told in a novel linked on the Pixiv site (in Japanese of course).
In short, "Mama" kept Kagome with Yuna in a locked play room with no windows and no way to keep track of time, fed them baby food and treated them like babies. Yuna seemed completely fine being and acting like a little baby, but Kagome missed the more adult behavior. She became sexually frustrated as her Master had usually stimulated her sexually every day, but whenever she tried to satisfy herself, Kagome was stopped by Mama every time. Mama eventually dressed both into matching romper suits she had ordered and took some photos (the first one of the gallery). The rompers were made to match a mascot character from an amusement park they visited. Mama had some photos of that occasion, and Kagome saw Yuna on those photos dressed in a romper suit and big bulging diaper in that amusement park. As it turns out, Mama was so wealthy and powerful, she just rented that whole park, so she could take photos with the mascot characters and play with diapered Yuna the whole time. Kagome started to get crazy from not knowing how many days have passed, the lack of "adult" stimulation and finally, when her Master picked her up after that week, she broke down in tears, crying all the way home.
And that's when the story in the images continues.
If you can do a better translation, or wish to translate in a different language, grab the Photoshop files from here: