It’s a quiet day in the life of professional assassin Mireille Bouquet, until she receives a mysterious e-mail. Sent by a Japanese schoolgirl called Kirika Yumura, the message reads “Make a pilgrimage for the past with me”. Mireille is ready to dismiss it- only to be transfixed by a haunting tune that accompanies the message.
Meanwhile, in Japan, Kirika bids goodbye to her classmates and starts walking home, only to find that an intrigued Mireille has tracked her down. Mireille demands answers, but Kirika says nothing, instead opening a pocket watch that plays the same familiar tune from the e-mail. With Mireille distracted, Kirika takes the opportunity to run away through an old building.
Determined to find out more, Mireille goes after Kirika and manages to find her- just as Kirika knew she would. But before the two women can talk, they are discovered by a group of men, who immediately prove to be of the “shoot first, ask questions later” variety. Whilst Mireille busies herself with taking them down, Kirika takes off again.
Going after Kirika once more, Mireille runs into more men, including a few who are already dead- could it be that Kirika killed them? There is little time for speculation, however, as Mireille bumps into yet another man. He puts his hands up in surrender, thus catching Mireille off guard whilst his cohorts attack from behind, disabling the young woman. Gun in hand, one of the men prepares to shoot Mireille, only to be shot himself- by Kirika. The girl proceeds to finish off the other men in an astounding display of killing ability, but when she is finished, she sheds a single tear- somehow she can do these terrible things, and yet she does not feel sorrow for them…
Mireille’s arm was injured in the fight, so Kirika takes the woman back to her house to treat it. The house supposedly belonged to the Yumura family; the story is that the parents left for America, leaving their daughter behind to attend school- but Mireille has done the research and knows this is all a front. She is more interested in the truth than in some elaborate cover story.
Kirika explains that she awoke one night in a strange room, her only memory that of a single word- “Noir”. Searching the room, she found an identity card with her photo that identified her as “Kirika Yumura”, whilst tucked away in a drawer was a gun- one that she soon discovered she knew exactly how to use.
Knowing there is one more piece to the story, Mireille presses Kirika to talk about the other item she found in the drawer- the pocket watch. Kirika takes out the watch and opens it once more. Listening to the music, Mireille has a flashback of her own- to a time when her younger self was clutching a teddy bear.
Having explained all that she can for now, Kirika asks if Mireille will help in unravelling the past. Mireille is initially reluctant, saying that she prefers to work alone. In the end, however, she is sufficiently intrigued that she will stick with Kirika for the foreseeable future- but there is a price. Kirika knows the truth about Mireille, and once the assassin has the answers she wants, the girl will have to be killed. Kirika is not afraid of this- in fact, she says that she is waiting for that moment.
Bidding goodbye to her school and her life in Japan, Kirika returns to France with Mireille to begin their journey. And so, a new and uneasy alliance is born, under the code name “Noir”…