Akiyama Rinko, often referred to as the Slashing Taimanin due to her skills of swordsmanship with her katana, which is apparently a family heirloom. Like many Taimanins, she attends Goshu academy with her best friend, Yukikaze, and younger brother, Tatsurou. Her ninja abilities are referred to as the "void arts". Some of her abilities include being able to increase her senses so she can see long distances, see at impossible angles, and through walls. She can also create portal that teleport her up to a range of 1 km.
Rinko infiltrated into the evil city as enslaved candidates for the brothel. There she learned a contract to become a whore comes with a cruel contract with a devil: a seal on her tongue to restrict any rebellious actions! Her body would explode once she make a disobedient move.
There's only one way to stay alive: become a submissive enslaved prostitute! Rinko had to earn money by working as a whore and get past a terrible lethal contract. In order to save Shiranui, there was no other way than to become successful lady of pleasure and make a lot of money. Thus her humiliating sexual training started under the threat of death...
At the end, Rinko is unable to saves Shiranui, and instead, got brainwashed by Real and becomes his sex slave.