Ai no Kusabi Series by Rieko Yoshihara

In the future, on a distant star lives a new society. Ruled by a computer system named Jupiter, men are divided into classes based on their hair color. The Blondies, genetically altered by Jupiter, are the highest class and occupy the capital city of Tanagura. Those with black hair, Mongrels, are forced to live in the slums, Ceres. Iason, the leader of the Blondies, encounters Riki, a mongrel, in the streets of Ceres one night and sets out to own him... moreIn the future, on a distant star lives a new society. Ruled by a computer system named Jupiter, men are divided into classes based on their hair color. The Blondies, genetically altered by Jupiter, are the highest class and occupy the capital city of Tanagura. Those with black hair, Mongrels, are forced to live in the slums, Ceres. Iason, the leader of the Blondies, encounters Riki, a mongrel, in the streets of Ceres one night and sets out to own him.---Taken from back cover:The Man's upturned blue eyes were so unimaginably beautiful that they could make anybody tremble with awe. In this moment, however, they also glimmered with an icy fire--perhaps revealing the fury of his wounded pride, or rather, a manifestation of his uncontrollable obsession.Ceres: a city without ethics or taboos, ruled by instincts and lusts. These are the slums--immutable, eternal, home to those poor, caged souls stricken with a perpetual melancholy.After three years, Riki unexpectedly returns to Ceres, but all is not well. The "Charisma" of the slums is a changed man. Faced with growing suspicion that he's lost his spark, and haunted by the memory of what happened during those three years away from the slums, Riki finds himself pulled into the escalating gang warfare as rivals attempt to wipe out his pack before they can regroup under their newly-returned leader. And then there is the frighteningly cold, regrettably familiar man he meets by chance one day: the beautiful Iason Mink. What secrets lie behind the smile of that bewitching Blondy? less

One night five years ago, Riki was wandering through the pleasure district of Midas, when he found himself in a rather dangerous situation. As a consequence, Iason, the genetically engineered elite "Blondie," has given him such levels of humiliation and unwanted pleasure that Riki's mind is still haunted by it---Taken from back cover:Riki found himself in an unusually talkative mood... moreOne night five years ago, Riki was wandering through the pleasure district of Midas, when he found himself in a rather dangerous situation. As a consequence, Iason, the genetically engineered elite "Blondie," has given him such levels of humiliation and unwanted pleasure that Riki's mind is still haunted by it---Taken from back cover:Riki found himself in an unusually talkative mood. In response to the frigid gaze falling on him as if from a great height, he gestured defiantly, not intimidated even by the ever-present air of omnipotence in Iason's cool voice.While cruising for cash cards from unwary tourists in the city of Midas, the slum mongrel Riki never imagined that he'd meet an elite Blondy like Iason Mink. Was it chance or the workings of fate that brought this unlikely pair together?Nine years ago, a stroke of luck landed the King of Bison a job as a courier--a veritable ticket out of the slums. He found himself under the employ of Katze, a man whose origins were not so different from his own. Inspired by this man's success, Riki learned the ropes and became known as "Riki the Black" for his exploits within the black market. But even as he moved up in the world, a shadow threatened to pull him down--a memory of the meeting he has with a certain Tanagura Blondy-- and leave him a thrall to its presence. Little did Riki know, it was more than just Iason's memory that enslaved him... less

A Blondie takes a street mongrel as a pet, and the entire city buzzes with the scandal. However, Riki, ever the defiant pet, appears to be losing his master's interest. Is he on the verge of being abandoned?

Released from Iason's curse, Riki is spending his days idly in the slums when he's drawn into a trap - is it a secret plot of uninvited visitor Kirie, or could it also be a cruel way to force Riki to choose between the body of his old roommate Guy and his own pride? Riki revives the memories of his three years of lust and masochism with Iason. Is freedom just an illusion?

After his release from house arrest and return to the slums, Riki's relationship with Guy has been awkward at best. Before they are able to resolve any of their relationship issues, the security forces of the notorious Midas cross the border for an all-out invasion. Can anyone survive the attack of such powerful forces?

Seeing Guardian's dark side in full, the pursued Kirie escaped to Riki's place. But Guy handed him over to the visiting Katz Leading to discord between Riki and Guy, Riki left the slums behind to seek out Iason's approval.

The feelings of anger and jealousy surrounding Riki's status as Iason's pet continues to fester, both amongst the Blondies and their pet. Riki is feeling more and more isolated, as he suffers from a serious stabbing and remains confined. Will Iason be able to keep hold of his beloved Riki, or will Blondie's society tear them apart? And what about Guy? Is he willing to walk away?

Riki's stumbled his way into the upper class's neighborhood?! Guy, who's hot on his trail, is shocked to discover that Iason is Riki's patron. However, before Riki's eyes, Iason announces "Riki is my pet" in a display of dominion over him. Blinded by his jealousy, Gai kidnaps Riki and challenges Iason to a no-holds-barred confrontation. Master and pet.. moreRiki's stumbled his way into the upper class's neighborhood?! Guy, who's hot on his trail, is shocked to discover that Iason is Riki's patron. However, before Riki's eyes, Iason announces "Riki is my pet" in a display of dominion over him. Blinded by his jealousy, Gai kidnaps Riki and challenges Iason to a no-holds-barred confrontation. Master and pet...love forged in the bonds of a twisted relationship - this is the stunning conclusion of Ai no Kusabi!---Taken from back cover:"When I was in Eos I thought I would never back down, never give in. Even in the last three years in Eos, I was a slumdog to all of them, but that was what I had pride in. ...But since coming to Apatia... I thought it was meaningless to keep holding onto that. And when I'm with Iason, my head spins and I can't help it."It dawned on Katze at last. The one who changed wasn't just Iason. It was Riki as well. "So you love him," Katze said matter of factly.Riki, the Ceres slumdog, has a new cage: Apatia, the place where the elites of Midas hide their mistresses--and their human pets.Iason Mink has allowed Riki to live in Apatia under the watchful eye of Katze. Determined to earn a measure of freedom by working as Katze's assistant in the underground again, even while remaining Iason's sexual pet, Riki tries to leave the past behind.But unknown to him, forces are at work that will make this impossible.Word is leaked to Bison that Riki has been spotted in Apatia, and once Guy hears this, nothing will stop him from going after Riki. As the Bison members reunite to try to take back their former leader, Guy makes a final desperate attempt to turn back the clock--to change things back to the way they were when Riki and Bison ruled the streets of Ceres.And what happens next--changes everything forever. less