Mama Reido vol. 1 Sakie Mama Hen ~Koi o Shita no wa Shin'yuu no Mama Deshita~

Sakie is smitten with the innocent spirit of her son's best friend, Mahiro, and recently has been writing her own online novels based mainly on Mahiro, which she enjoys with other like-minded rotten girls.
But one day, she suddenly receives a threatening email from someone who knows about her online writing activities.
"If you don't want people to know about it, get Mahiro to become sexually active and make a video of it," was the threatening message, which left Sakie shaken.
If her corrupted otaku hobbies, which she has kept hidden all this time, are revealed, her current happy place in life will be gone.
Following the instructions in the email from the mysterious blackmailer, Sakie targets Mahiro, who has come to visit as usual.

[From Dlsite]