No.1 The Clock Keepers

「三人の時計守」
The three clock keepers is the first of the Seven Mysteries.

Unlike the other school mysteries, the clock keepers consist of three members. They represent past, present and future.

Their arc starts in volume 5, where Nene and her classmates found their belongings in class in ruins. Expired bento boxes, dust piling up like snow, mold on things and a plant's sudden growth spurt.

Upon seeing this, Nene went to consult Hanako. Kou then also comes rushing in, with pictures of his friends who have turned into old grandpas with beards. Hanako then explains that the three clock keepers in Aoi's story can control time. One who turns back time, stops time, and moves time forward. The three conclude that this is the work of the keeper who moves time forward. They head to find the clock keepers, but Hanako does not know where their boundary is located at due to a bad first impression where he calls their powers "awesome" and says "You can do all the pervy stuff you want!!!", causing the keepers to 'never want to see him again' and refused to tell him where their boundary was.

Hanako only knew that the clock keeper who rules the present was said to be a student in Kamome Gakuen. He feels the presence of a supernatural in Nene's class and calls Aoi suspicious because her belongings wasn't affected by the incident. In an attempt to communicate with Aoi and getting information out of her, Hanako possessed Nene for a bit.

Akane then later slaps Nene and shook him out of her body, which Hanako said was something no normal human could do.

Hanako then later uses Akane's love for Aoi to his advantage by putting Aoi in danger and forcing Akane to use his time-stopping powers, exposing him as the second clock keeper who rules over the present.

Akane then tries to catch Mirai, who is the clock keeper that rules over the future. Mirai usually wears gloves to prevent her from touching anything and turning time forward, and Kako usually keeps Mirai locked up in their boundary, but Mirai got away and started causing a commotion.

Akane also explains that his position as the second clock keeper was something he was scammed into, where Mirai and Kako set up a situation where Aoi was going to get hurt and made Akane want to stop time.

The plan worked successfully and he made a 6-year contract with the clock keepers, to be part of mystery no.1 until he graduates. He describes his job as being "the other clock keeper's slave."

The First School Mystery oversees the "Time" aspect of Kamome Academy.

Boundary
The boundary of School Mystery Number 1 is unknown, so is their Yorishiro.

The Rumor
Japanese=こんな噂知ってる？

七不思議の一番目

三人の時計守

この学園のどこかにある大きな大きな古時計

それは学園で流れる”時間”そのもの

その針を動かせば学園の時間を自由自在に操れるの

でもね

大時計には守人がいるのよ

それぞれ過去　健在　未来を司る三人の時計守

断りなしに大時計に触れた者は

時計守達に生きる時間を取られてしまうー|-|Official English Translation=...Have you heard the rumor?

It's school mystery number oneー The three clock keepers.

There's a big, big old clock somewhere in the school.

That clock is time itselfー the time that flows through the school.

If you move the hands of that clock, the school's time is yours to command.

But you see...

...There are guards watching over the big clock.

They are the three clock keepers who represent past, present, and future.

If anyone touches the clock without their permission...

...The three clock keepers will steal the time from that person's life...! Current Representative of the Mystery