Hi there
I'm for an hentai manga, help me please
It begins with the mother teaching her daughter (virgin) with Bondage, BDSM
Then, the mother finds her daughter's schoolmate to be her master but at the end the master to be become a real sadist

The oneshot from Tsuma-Monetize comes to mind for what you're talking about......it's out there under "Buta-san to Oyakodon | The Pig and Oyako-don" and was scanlated by desudesu back around July of 2015. And yeah, maybe it's not it, but it sounds similar......mother/daughter pair, both into bdsm, one of her schoolmates being brought home to get turned onto being their dom......so yeah, maybe, it popped into my head when I read your description and now it's the only one I can think of 😀

Not this one ,)

M Haha Musume Choukyou Nikki ??

Yes, that one.

i believe i had read it before but not from my storage, and when i read your reply my memory confirms it to be true.

What a lustful drawing style. It is old and dirty but kind of "never die"... or perhaps "irreplacable"??

XP