Mirai is a very small girl. She has long brown hair tied in pig tails — which are each as long as her height— with a hair ornament that resembles the hands of a clock at the ends. She wears a crown-like ornament atop her head and has long fringes on either side of her face. Her eyes are a dark turquoise, though they are rarely open as she is usually shown smiling or laughing.
Mirai appears to wear three layers of clothing: a dark blue outer coat with a hood, a brown-colored garment with a reddish trim in a diamond pattern, and a frilly long-sleeved white dress underneath. A small golden pocket watch hangs from her collar, with a pair of hanging ornaments on either side, attached to the front of her cloak. She wears black clog-like shoes with "one" (壱) inscribed on their soles.
Mirai is usually required to wear gloves to prevent her from using her powers, though she is not shown wearing them onscreen.
Mirai is mischievous, cheerful, and energetic. She enjoys turning time forward with her powers and appears to consider the elderly and wrinkled people cool. Mirai speaks in a somewhat childlike manner, referring to herself in third person.
According to Akane, Mirai's main trait is being dimwitted. She is also a glutton, likes grooming herself, and is very nimble. Akane likens her intelligence and speed to that of a mouse, which seems to be true since she is able to be caught using a strategy that Nene has also used on her own pet hamster.
However, Mirai does have a serious side as well, which is seen when she is unable to turn Nene's time forward and immediately realizes the implications of this.
Number 1's Powers
Mirai governs the future as the third of the three Clock Keepers. Like the other Clock Keepers, a clock face appears above or on the target of Mirai's power when she turns their time forward. Mirai is often shown directly moving the hands of these clock faces to manipulate time.
Mirai is able to turn time forward for whatever she touches, causing objects to decay, window glass to break, and potted plants to grow into trees. She can also turn students into elderly people, though their bone and facial structures do not change. In most cases, the people affected remain in the same clothes as before (with the occasional addition of a walking cane), but Kou has a different outfit after she turns his time forward and is also able to use new skills he will learn in the future.
Despite her childlike appearance, Mirai is very powerful, only becoming tired after turning much of the school's students into elderly people. Hanako also notes that not many supernaturals aside from the Seven Mysteries would be capable of such things. However, she has difficulties turning time forward for people with exorcist lineages such as Kou, who only gets aged forward by several years rather than by decades. Mirai also cannot turn time forward for people who only have short amounts of time left in their lifespan, and they appear to merely be rendered unconscious instead.
Mirai is very swift, easily evading capture by Akane, Hanako, and Nene. Though Kou manages to catch Mirai at one point, she still escapes by using her powers on him. Akane's power to stop time does not work on Mirai. However, Mirai can be trapped by a lightning cage, such as the one Kou is able to generate in the future. Kako is also able to undo Mirai's changes by reversing time, on an individual basis or for the entire school. In addition, because Mirai needs to have direct physical contact with others to use her powers, she cannot use them if she is wearing gloves.
- As she doesn't have a given name, Akane dubbed her "Mirai." This is because, even though it is written in katakana (ミライ) and therefore technically has no English translation, Mirai's name is pronounced identically to the Japanese word for "future" (未来), referencing her future-controlling ability.
- Her favorite snack is agar-agar (kanten) jelly.
- Her latest concern is that Nene is the only person she cannot make wrinkly.
- Mirai's pocket watch appears to make an audible ticking sound, which gives away her position in the candy bag in the Student Union room.
- Mirai also appears along with Akane in the back cover extra comic of the Houkago Shounen Hanako-kun volume.