I'm not saying the plot you describe doesn't exist, but usually the way I've seen it is that the mom/sister/teacher/friend/etc. intervenes to "save" the bullied guy but then the bullies fuck her and then bring the loser in to witness his love/hero get punished for intervening. Or, the loser gets lucky with the girl and the bullies notice their happiness and decide to force themselves on her to take away losers happiness.
I can't think of one I've seen where the loser invites the bullies to join in.
Omg, where have you been. It has been part of JAV movies for years.
This one a SUPER one and a classic, Ure-014. Bullied nerd gets the ultimate revenge to bullies with their moms and then share his "gifts" with his bullies... their own moms!
This is seriously a fun, twisted movie that gets a little bent towards the end with something that looks like part of the SAW series, except no violence
But its still a good watch.
Also, then JUL-657.
It's pretty good because of the actress Isshiki Momoko. But I'm no fan of the "bullied kid" giving his tormentors gifts like this
Also, also this one STARS-375 with Iori Kogawa, somewhat bullied cousin, yes she's a mean drunk but nice otherwise, but it doesn't stop twisted cousin from having s*x with her... because she's a heavy sleeper. And then he decides to sell her for money. Again sharing his gifts.
DVDES-699 this one is a shota. Basically, he is bullied kid.
After the main bully mom scolds her son, the "bullied" kid turns into a snake and decides to get revenge on the main bully with his innocent mom.
He also decides to impregnates her and makes her his cum dumpster...
and yes, he also shares his "gift".
But to one of your point.
There is another movie with this same shota and in that one he does the same, except 2 things different.
1. He is the bully. And the mom and son.
2. the ending is even more twisted.
The ending??? Well, the mom is left sex crazed for sex.
pregnant... with BIG belly...
Getting f*** by her son in the closing scene.
Mom is teaching her son s*x... and the baby is her son..
Which is just twisted shit.
Yes all of this has been part of JAV for a long time.
There are so many more to list but this is taking me away from subbing now.