いつまでも僕だけのママのままでいて！ ～ああ、良いよママ！もっともっとしゃぶらせて！！デリバリーママがストライクゾーン過ぎて僕の股間はもう限界！！！～

It all began with a leaflet.

"Delivery Mama 'Mother' Business service
Housework - Cleaning - Childcare
On the behalf of those who are busy, we will fill for them in as your mothers."

It was a flyer for housekeeping business service, a new agency just started in this area.
The normally apathetic protagonist held it in his hand, and called the number that was written on the leaflet.

Official Site