Kako

Kako (カコ or 過去) is a supernatural who controls the past as one of the three Clock Keepers, along with Mirai and Akane.

Appearance
Kako is an old man with a long braided beard (with a bead-like golden ornament near the end), moustache, and slicked-back hair.

Kako has an asymmetrical owl-like mask with a long hooked nose, similar to Akane (though Kako does not remove his mask). He uses a cane (resembling the hand of a clock) in his right hand. Though Kako appears to be somewhat hunchbacked, he is taller than even Akane.

Similar to the other Clock Keepers, Kako has a pocketwatch with a chain, though the clock face appears to be inversely coloured compared to Akane's, with light lettering against a dark background. Kako typically holds this pocketwatch in his left hand, sometimes storing it within his right sleeve.

Kako wears a long dark cloak with a hood, which is light coloured with a pattern of small triangles on the inside (presumably in similar colours to Akane's, though it has not been shown). On the front of the cloak, there is a golden braid between two tassels at the lapels, though Kako's cloak is completely closed, unlike Akane's. Kako also appears to be wearing a dark collared shirt under the cloak, though it is not clearly shown.

Personality
As the oldest among the Clock Keepers, Kako acts as their de facto leader.

According to Akane, Kako is more reasonable than Mirai, but he still makes demands of Akane, such as instructing him to recapture Mirai after her escape.

The Three Clock Keepers Arc
Kako doesn't show up until near the end of the arc, when Hanako, Kou and Akane finds out the truth about Nene. He showed up, reverting Kou's time back to present. Kako then turns back time before Mirai wrecks havoc, ending the three clock keepers arc.

Mirai
Mirai seems to be close to Kako, referring to him affectionately as "Ojii-chan", and Kako sometimes carries her in his arms. Several years ago, Mirai worked with Kako to recruit Akane as one of the Clock Keepers, by using her powers to stage Aoi's near-accident while Kako spoke to Akane. To prevent Mirai from using her powers, Kako usually keeps Mirai in their boundary, though she escaped from him once, triggering the events of the Clock Keepers Arc.

Aoi Akane
Akane does work for Mirai and Kako under his contract with the Clock Keepers. As Kako appears not to have a name, Akane calls him Kako (literally meaning "past" in Japanese) or more derogatorily as "that rotten old man".

Hanako
Though Hanako is the leader of the Seven Mysteries, the Clock Keepers (presumably led by Kako) refused to see him again or tell him the location of their boundary after their first meeting. However, Kako still obeys Hanako's instructions, as seen when Hanako told him to reverse the school's time to before Mirai's escape.

Number 1's Powers
Kako governs the past as the first of the three Clock Keepers. Like the other Clock Keepers, a clock face appears above or below the target of Kako's powers when he turns their time backwards. Unlike Mirai, Kako does not need to directly move the hands on these clock faces to manipulate time (for example, Kako is able to turn Kou's time back just by touching him on the head).

Kako is able to turn back time on both small and large scales, reversing the entire school's time by almost one whole day. This suggests that Kako may be the most powerful among the three Clock Keepers, since both Akane and Mirai are only shown manipulating time on a much smaller scale.

When Kako turns back time for an individual, the effect seems directly opposite to Mirai's powers, and the individual retains their memories.

On the other hand, Kako can turn back time for the entire school, including all the people and objects within it. This reverses both the regular passage of time, as well as changes caused by both Mirai and other supernaturals (such as the chandelier Hanako broke using his hakujoudai). As a result, the events during this period are erased from almost everyone's memories, with the exceptions of supernaturals and humans with extremely high spiritual power. Interestingly, though Mirai's powers do not fully work on Kou due to his exorcist lineage, Kako says that Kou's memories would also be erased by the time reversal, which is only prevented by Akane using his powers on Kou. In addition, even after Kako reversed time, Nene still seems to remember the day's events until the point where she was knocked unconscious, although she is not a supernatural or a human with high spiritual power (like Akane and Teru respectively).

Presumably, Kako's powers also work only within the school, like Akane's.

Trivia

 * "Kako" is pronounced identically to "past" (過去) in Japanese, and is written either in kanji or katakana (カコ) during his various mentions/appearances.
 * When Kou asked him whether if he was called "Kako" because he can turn back time, he added that a name doesn't matter much for supernaturals