Kuni's plan turning on him in Kosuke Suzuki's Stop the Bitch Campaign (2001).
Released recently on dvd in Hong Kong under the same title as the new 2009 version by the same director, Stop the Bitch Campaign Version 2.0, but it's actually the original from 2001. Kenichi Endo plays Kuni, the strange, to say the least, manager of a phone sex service who discovers that a group of young girls is using his service to black mail his middle aged male clients by bringing gangsters to their arranged meetings.
That is when Kuni hatches the brilliant plan to stop the prostitution, save the country and become a hero of Japan by meeting the girls himself and violate them with his special kind of s&m and then leave without paying. After torturing a virgin who tries to commit suicide afterwards, and who happens to be the little sister of the leader of the blackmailers, Kuni is the one being hunted by the girls instead of the other way around.
I've always liked Kenichi Endo and his weirdo characters even though he sometimes goes too far into just screaming and mugging territory. Going into Stop the Bitch Campaign, I was a bit worried he'd be as bad and annoying as in the first sequel, Stop the Bitch Campaign - Hell Version (2004) starring Aoi Sora, but in this first installment he stays just insane enough for it to be entertaining. For anyone looking for something serious, Stop the Bitch Campaign can't be recommended, but if all you want is Kenichi Endo in a thong and eye make-up torturing high school girls and a guy getting firecrackers up his butt, this is the film for you. Even if it brings up issues like compensated dating (enjo kosai) and the immorality and greed of both men and women the film is, just like Kuni's plan, just an excuse to show/get some sex.