Irene Diaz (アイリーン・ディアス, Airīn Deiasu) is an esteemed opera singer and actress. After she and Grimsby Keane, another celebrated individual, separated, she formed a relationship with actor Julius Pitt.
Irene is a beautiful young woman with lavender eyes and long, wavy blond hair; her hair is worn in a ponytail and crowned with a garland of lilac flowers. She typically dons fancy, distinctive dresses. Her accessories include a string of pearls, long dangling earrings, and lengthy gloves.
Irene is a calm, quiet, and courteous individual; only when she is repulsed with another person does she react emphatically. For example, when Georg von Siemens had continued to grope her despite her insistence that he stops, she slapped him across the face and condemned him for his insolence. However, when reprimanded for her actions, she would be genuinely apologetic and thank those that assisted her.
Patient and forbearing, Irene often attempts to soothe the bellicose Grimsby Keane whenever he gives vent to his anger. She is also very sensitive to macabre matters, such as homicide, and would become agitated and slightly faint at gruesome details like the inevitable decay of corpses. Additionally, Irene is insecure about her age, and thus, she tends to consume the anti-aging substance, red perilla, to keep herself youthful on the exterior.
Phantomhive Manor Murders Arc
Irene is invited to a party thrown by Ciel Phantomhive and mingles with Grimsby Keane, her significant other, in particular. She and the other guests exchange greetings and commence introductions. When the guest of honor, Georg von Siemens, continues to touch her lecherously, despite her persistent demands that he ceases such shameful act, she becomes quite distressed; as a result, she slaps him and berates him for his disrespectful behavior. Georg responds by throwing a glass of wine at her, and Ciel intervenes and shields her, bearing the brunt of the attack. Incensed, Grimsby throws a bottle of wine at Georg's head, but Sebastian Michaelis catches it and sensationally fills wine glasses with it. This establishes tranquility among the guests, and they resume the revelry.
In the midst of the festivities, Irene and the other guests hear a loud scream from Georg. They rush to his bedroom; inside, they discover, to their unanimous horror, that Georg has been killed. Grimsby suggests that they refrain from moving his corpse until the Scotland Yard arrives, but Baldroy sternly disagrees; he explains that the body will rot fast if they do not immediately transfer it to a cold, dark room. Upon hearing that the body will rot, Irene gets anxious and unbalanced. After the said body is moved to the cellar, Irene and the guests speculate on how the murder happened in a locked room scenario. Everyone is, then, asked for his or her alibi. Grimsby claims that he and Irene were in the Billiards room at the time of Georg's murder. They eventually narrow down the prime suspect to Ciel, and when one guest is asked to maintain a vigil over him, Grimsby states that he would not allow for Irene to be by herself. After they decide that Arthur Conan Doyle will keep a watch over Ciel, Irene and the other guests are escorted to their respective rooms.
The next morning, Irene and the other guests discover the brutal murder of Sebastian Michaelis. Eventually, they resolve to move Sebastian's body to the cellar for the time being, and Irene and Grimsby follow Charles Grey to the dining hall. At the dining table, Grimsby asks Irene why she has not touched her food, and she replies that she is not very hungry. Grey offers to eat the leftovers, and when Irene is about to hand her plate to him, he clarifies that he wants the plate next to her. They, then, collectively realize that it belongs to the mysteriously absent Patrick Phelps. They opt to check on Patrick, who was assigned to Ciel's bedroom. When they find that the door is locked, Grey swiftly cuts it down. They hurry inside, and discover Patrick's corpse.
Soon after, they have dessert at the drawing room, where they discuss about the three murders. Ultimately, the group allow for Arthur to dictate their actions from that time on, as through deductive reasoning, he is the only one who could not have committed any of the crimes. They decide to investigate Sebastian's body in the cellar, but Arthur asks for Irene to stay behind with Grimsby, saying that requesting a woman to accompany them to inspect a corpse would be inappropriate.
Subsequently, Arthur explains to all the guests that their rooms and belongings must be checked, and they give their consent. Ran-Mao and Mey-Rin search Irene's room. Mey-Rin voices her surprise regarding the revelation that Irene and Grimsby are lovers; Irene divulges the fact that since she and Grimsby are twelve years apart, she finds it too embarrassing to tell others about their relationship. Mey-Rin is astonished, as Irene appears very youthful. Ran-Mao, in the meantime, tends to leave things open after she is finished looking through them, and takes the liberty to sift through Irene's trunks as well; she even puts a pair of Irene's undergarments on her head, much to Irene's and Mey-Rin's alarm.
In due course, the group gathers at the drawing room once again. Soon after Lau suggests the existence of a "thirteenth person," Jeremy Rathbone appears. They interrogate him to see if he is involved in the murders; Jeremy explains that he was watching The Lady of the Lake at the Lyceum Theatre the previous night, and Irene confirms that it is, indeed, being performed in London. After they substantially verify Jeremy's innocence, Jeremy is allowed to lead the investigation. For dinner, the group eats a scrumptious steak meat the Phantomhive servants have prepared. Lau presses for the truth behind the incidents, but Jeremy advises them to not be hasty.
While Jeremy implements a plan to catch Patrick's killer, Irene and the rest of the group gather in Karl Woodley's room to wait. Tanaka appears at the door to announce that they were successful in capturing the killer; Grey, then, declares that they have brought the killer along, which frightens Irene. Jeremy reveals that Patrick's murderer is a snake. They reason that the snake must have been smuggled from Africa, which shifts the attention to Karl, who specializes in African trade. Jeremy proceeds to thoroughly present evidence supporting the idea that Karl is the murderer. Subsequently, Karl is detained, and Irene and Grimsby express their relief.
Finnian, then, inquires about the bottle of deep red liquid belonging to Irene that Mey-Rin had earlier stumbled upon. Grimsby angrily confronts them for holding doubts about Irene, though she tries to calm him down. Jeremy clarifies that the liquid contains an extract of red perilla which brings about an anti-aging effect. Abashed, Irene admits that she drinks the substance so that she can remain forever young with Grimsby. They, then, use some of the liquid to toast in celebration of the solving of the crime. As soon as the sky clears up, Irene leaves on a carriage with Grimsby.
Public School Arc
Irene is travelling with a fellow actor named Julius Pitt—who is also Irene's current love interest—to where her stage performance, Romeo and Juliet, would be taking place. Abruptly, the carriage tips over, and Sebastian Michaelis quickly goes to their aid. Irene worries that she might miss her performance and be seen with Julius, as it would generate bad publicity, since he works for a rivalling theatre company. However, Sebastian assures her that he has thought of a good solution. They, then, make an exchange: in return for Sebastian getting her to her show, Irene would help him encourage the sales of the new Funtom Corporation product, Lily of the Valley, a type of women's perfume.
Sebastian, soon after, vigorously drags the carriage all the way to the theatre, much to the shock of onlookers. Irene dramatically lunges onto the stage, while sitting atop a large unicorn promoted by the Funtom Corporation; Lily of the Valley cards are disseminated and scattered widely onto the audience. Irene, then, seamlessly performs as the character Juliet, garnering acclamation from the impressed audience. Out of gratitude, she kisses the unicorn costume Sebastian is disguised in for transporting her to the stage on time.
- According to the official Kuroshitsuji character popularity poll, Irene is the forty-sixth most popular character in the series, with four votes. She shares this spot with Snake's snakes, who also received four votes.
- Irene may possibly be a reference to Irene Adler, who is also an opera singer; she is a fictional character featured in the Sherlock Holmes series written by Sir Arthur Conan Doyle.
- She stars in the Duchess of Padua, a dramatic play by Oscar Wilde. This play was staged for the first time in 1891 under the title of Guido Ferranti.