https://www.dlsite.com/maniax/work/=/product_id/RJ01131112.html
https://www.dmm.co.jp/dc/doujin/-/detail/=/cid=d_334448/
https://anam111y.booth.pm/items/5395552
https://www.melonbooks.co.jp/detail/detail.php?product_id=2285571
https://www.digiket.com/work/show/_data/ID=ITM0269918/

Base +22

This doujin has some sort of happy ending if someone is wondering.

The plot in short:

-Mash loses her ability to fight, but she wants to be useful to Ritsuka
-She goes to Kiara who is "therapist", and when Mash closes her eyes, Kiara shows her visions of being gangbanged
-Kiara says that Mash can be useful to him with her body
-One month later Ritsuka wants to spend time with Mash, but she says she have her counselling session
-Ritsuka spots her being gangbanged and wants to save her but he is being held up
-Mash is happy that he can see her and explaind that she is helping him by managing desires of men in chaldea since this is closed environment
-After gangbang she precises that Kiara told her that Ritsuka has NTR kink and she wanted to make a good show for him to be useful to him as slut
-Then Mash gives him handjob and promises to handle his ejaculations everyday
-Then...Ritsuka opens his eyes and it seems now he had "vision" in Kiara's "therapy" just as Mash had before

Base +6, IggyTheDog +8