Oseiko Kurotsuki was born in the forests of Hokkaido, in an isolated village home to the descendants of the ninja clan Akuhi Ryu; Oseiko's ancestors was its clan leader, a young woman named Misao, and her great grandfather "The Revenant" Shaed Bloodgrave. At an early age Oseiko began to learn the craft of ninjitsu, quickly taking to the fighting style and becoming a genin kunoichi ninja at the age of fifteen. In celebration of her newly acquired status, Oseiko was given her title as the Black Widow; a large tattoo of a black widow spider was etched into her back, stretching from her shoulders all the way down to her thighs. At the age of sixteen she was visited by her great-grandfather Shaed, offering to her elders to continue her training by entering her into the world of professional wrestling. Enticed by the idea of working with her beloved "Shaed-sama," Oseiko convinced her elders to let her go with him. And so Oseiko became Black Widow, the ebon-clad ninja of the gothic stable of the Knight Cross, along with Shaed, the wraith Sasori, and the pyrokinetic Kaye. Originally planned to enter the EAW, the federation suddenly went belly-up, going bankrupt. So Shaed brought his Knight Cross to the now-defunct federation known as the IWF. Black Widow already made quite the impact in the IWF, proving the critics wrong as she defeated established Superstars, and even survived a Battle Royale, using her exceptional speed and agility to become the first female IWF Cruiserweight champion; despite losing it two weeks later, Black Widow had still made history.

Eventually the EAW was rebuilt, and Shaed moved the Knight Cross to it. It was there that Black Widow met fellow EAW Elite "Code Red" Michael Connelly. The two almost immediately fell in love with one another, becoming one of the hotter couples of the federation. Eventually the two became married, and remains a happily married couple.

The Knight Cross eventually broke up and Oseiko re-evaluated herself in the EAW, and she and a newcomer to the EAW, Akiko, formed the tag team known as Kyouki Shoujo. And when Shaed died saving the world from the demented evils of his son Ryokami, Oseiko suddenly found herself imbued with a power inherited from her great-grandfather; a healing factor that enabled her to heal and recover from most injuries at a rapid pace. Oseiko opted to use the power to the fullest as a part of Kyouki Shoujo, using her own brand of Extreme known as "Ekusutoriimu."

Oseiko has had much happen to her over the course of her career... she has reached the pinnacle of her training, becoming a jonin kunoichi ninja, a master of her craft. She has actually died saving her friend from being hit by a bus, and has been mysteriously resurrected, and she had even accidently killed another member of her clan and was forced from the Akuhi Ryu. Even more recently, Oseiko had lost her trademarked black widow tattoo when attacked by Ryokami and his concubine Leatherstitch; the sexy Cenobite had used her hook chains to strip Oseiko completely of her skin. The combination of her healing factor and the EAW's chief healer Aerith Gainsborough proved to save her life, but with the new skin came the loss of her symbol as a part of the Akuhi Ryu, her ties with her former clan completely severed. However, Oseiko was visited by her mother, the head of the Akuhi Ryu, Azumi Kurotsuki. Azumi told her daughter that the old ways were past, that she looked to Oseiko to raise and train four genin ninja, children from ages 8 to 15. She also said that the rest of the Akuhi Ryu had commited seppuku and that she herself had ingested a poison. Azumi collapsed, and as she lay dying in her daughter's arms she managed to say that she was proud of her, and that she loved her, just before passing on. And so, Oseiko had gone about the task to raise and train the five survivors of the Akuhi Ryu, realizing her dream to form her own clan known as the Kurokumo Ryu.

Her title reigns have been nothing short of impressive, recently using her skill as a ninja to devise counters to moves no one has seen and her danger-sensing sakki to become one of the more exciting Extreme Champions the EAW has had. With her continuing climb up the ladder, experts had speculated that it would only a matter of time before Oseiko became EAW World Champion and reach the upper echelon all Elites dream to touch. And they were right, as Oseiko defeated nWo leader David Flair, reclaiming the EAW World Title for the EAW and reaching full circle in the EAW; Oseiko is now the first EAW Elite who can lay claim that she has held nearly all the titles, past and present; the only title she hadn't won was the recently reinstated EAW Women's championship.

Her title reign was short lived, as she was challenged by her own husband, "Code Red" Michael Connelly. Despite her defending the title under a 24/7 ruling against all challengers in and out of the EAW, critics still considered her as a transitional champion, and even her closest friends thought it was too soon for her to be champion. Nevertheless Oseiko fought diligently at EAW Aggression with some last minute training from Shaed Bloodgrave. But sadly she couldn't retain the title, losing it to Connelly.

Recently, while she and long time friend Seijimei Kuroido were competing in a match together, Booker Waters had attempted to interrupt the match by staging the kidnapping of one of her students. However, little did he realize that a rival of the Akuhi Ryu had intercepted the true kidnapper, putting Oseiko's student in mortal danger. Oseiko had no other choice but to end the match prematurely to rescue her student, and despite all her attempts to prevent any fatalities, Oseiko was forced to kill the clan rival in order to save her student. With blood on her hands, Oseiko left the EAW for a period of time, taking refuge in the hidden village of Konohagakure to purify her soul and rediscover her purpose. However, she had picked the wrong time to visit, as forces compromised of the Land of Sound and Sand conspired to invade the village. Oseiko had did her part in trying to defend her adoptive village, and during the conflict, had fought a young kunoichi named Kin Tsuchi. Having easily bested her, Oseiko remained non-violent, offering her life so that she could become stronger and perhaps one day defeat her, but Kin was suddenly summoned away to be used in the fatal Impure World Resurrection jutsu used by Orochimaru. Upon discovering Kin's corpse, Oseiko mourned her, and had taken it upon herself to take her body back to the Land of Sound. A day afterwards, she was visited by Kin's spirit, when Oseiko had contemplated giving up being a ninja. With words of encouragement, Kin resolved Oseiko's strength of will, telling her to continue to fight, and with that, Kin left, leaving behind her clan headband with a deep scratch through the metal plate, a sign that even in death, she had severed her ties to the Land of Sound; Oseiko keeps the headband to this very day, and wears a symbolic design of it in her current ring attire. And accompanying her from the Land of Fire was a black-furred cat she called Kizuhoshi, named so for the star-shaped scar over her left eye; Oseiko's new feline compatriot seems more than she appears as well, much smarter than any average cat. In turn though, she had left her students in Konohagakure, hopeful that they could learn to be better ninjas there than under her supervision. She also brought with her knowledge of two basic jutsu she had learned while in the Land of Fire; the Kage Bunshin no Jutsu (or Shadow Clone Technique), the Kawarimi no Jutsu (or Substitution Technique), and the Henge no Jutsu (transformation jutsu) were the only three jutsu she was able to learn during her short time in the village, and she rarely uses them in the ring; more often than not, she chooses to utilize these jutsu in mind games against her opponent.

Recently, however, she had made the decision of saving the life of the Sound Ninja Tayuya, and her actions had caused the Hidden Leaf Village, currently at odds with the Sound Village, to take equal action. After a brutal match against "The Blue Tygress" Trish Stratus, after the pay-per-view event itself, Oseiko was captured by Nara Shikamaru, Choji Akimichi, and Ino Yamanaka and taken to the Hidden Leaf Village to answer accusations that she had willing aided Sound Ninja, an accusation that Oseiko freely admitted to. In the end, Oseiko was found guilty of aiding enemies of the Hidden Leaf Village, but not guilty of being a traitor, in lieu of the fact that her kindness and show of bravery had shown to learn Tayuya of some humility; the sentence being that Oseiko was exiled from the Land of Fire. In this, Oseiko was freed and was allowed to return home.

With her latest misadventure behind her, Oseiko plans to focus more on professional wrestling; aiming to claim the one title that had eluded her for so long; the EAW Women's Title, now held by Trish Stratus.