Yuukai Anna

Mireille Bouquet is a professional assassin, and a very good one at that. But when she follows up an e-mail from a young Japanese girl named Yumura Kirika, inviting her to take "a pilgrimage to the past", her life becomes even more dangerous than it already is. Now, with a haunting melody invoking the memory of an event long past, Mireille and Kirika decide to work together to find the truth about a thousand year old organization that has controlled both of their lives since before they were born. And the only clue in their search, the only thing Kirika remembers about herself, becomes their working codename: a name designating an ancient fate, of two maidens who reign over death--Noir.

In the near future, a girl yearning for death and a robot who has been near her since she was a child continue moving in eternity.

It's sometime in the future and the story starts off with Kei and Ai running for their lives. Ai is a little girl who holds a terrible secret which could destroy the current world. The world is now populated by Headmeters, people who have psychic powers and their strength is shown on their forehead when they fight. However, Kei was an experimental subject and his strength never went above level 5 while other surpasses his ability effortlessly. While escaping, when in desperate moments, Kei could increase his ability to infinity when Ai is in trouble. The one who's after her have a deep secret, aided by a small dwarflike man living in a robotic suit. Eventually Ai is captured and Kei, a sherlock holmes detective and another Headmeter who was converted to the good side when Kei unleashed his horrible powers through Ai must go and rescue her. Together they must save Ai and the secret which she holds. What is the secret of Ai? Who is she?

Yearning to get along with others and not be disliked, first-year high school student Hiiragi finds himself unable to say no whenever someone requests something of him. One summer day, while unsuccessfully carrying out yet another request, he encounters an oni girl named Tsumugi, who has come to the human world to search for her mother. She does whatever she pleases and is the complete opposite of Hiiragi. Snow mysteriously begins to fall... and their adventure begins.