Taken from CMX website

Kazuko is a high school senior who has no idea what she wants to do in the future. Alone one day after school, she discovers a broken beaker in the science lab. She smells something sweet in the air, passes out, and finds herself transported back to her own past! Will Kazuko use her ability to travel through time wisely or selfishly?

Based on the 1965 novel.

After 17 ordinary years on Earth, Makoto Konno's journey was about to be ended by a freak accident. Then, life gave her a reset button. With her new found time-leaping powers, she immediately sets out to wipe off all the little annoyances in her daily life, from failing grades to iffy relationships she can't handle. But as her time-leaps get more frequent, she is forced to realize that every change she makes has profound repercussions that she can't foresee...and should her powers fail her, the consequences could be disastrous...

This was set as a prelude to the 2006 animated film of the same title, which was in turn loosely based on the 1965 novel.

Collection of three stories:

1-4. Toki wo Yuku Uma
Four-part tale of love and loss featuring a musical snowglobe horse that passes through many hands on its journey around the world. It evokes old memories and half-forgotten dreams in those who gaze into it, thus changing their lives forever.

5-10. Star Kid no Fumou na Houken
Comic adventures about a group of elves.

11-33. Keiko-chan no Kyouji Seikatsu!?

Takemiya's last manga volume.
Autobiographical vignettes about life as a manga professor.

Story about a mirror princess/demon. It seems that a new condo building was built on a certain location where this princess was housed and worshiped with a stone monument but it was moved due to the new construction.

One room in particular seems to have a direct link to the princess who calls herself the owner of the pool of time. Beware when mirrors are placed opposite of each other because you may just be drawn in her world and powers.

In her Ay (Aniversary Box - 2013) the author wrote that this work is unfinished.

From Fantasyshrine:

High School Senior, Yokozeki Haruhito has always been watching the teacher-in training, Arisawa Yuya. However, this doesn't go unnoticed by Yuya's cousin, Yuma. Yuma volunteered to be Yuya's substitute. Things started to escalate when one day Yuya walked in on them while they were kissing...

From Chibi Manga
After a certain boy request for protection from class rep...her luck has been skyrocketing?

From JShoujo:

If you wanted to find a good-looking guy, where would you look? The answer is easy – it’s the “Tokimeki Campus”. Here, the whole place is overflowing with princes! However, most of them already lead a wonderful love life. Starting from a narcissist, you’re going to be introduced to the colorful stories of the campus!

Arare knows she's a rain fairy - her mother is clearly not entirely human but on her first day of high school she definitely does not expect to enter the Otherworld. Nor does she expect her teacher to have a ridiculously long neck, or her classmates to be a variety of ogres, snow demons, cyclops, ghosts, mist, or the twin-tailed cat, Kiri, and long-tongued girl, Pero, who befriend her. Nor does she expect the veil between the worlds to close behind her, leaving her stranded in this school for girl monsters.

"Is this a dream or a miracle?"

A plain and inconspicuous girl, Mari Jingyouji, was confessed to by Shiger Hanamizuki, the most popular boy in the class, after she saved him from dying in a car accident. But there is a reason why Mari is not happy. That's because, her family are all "○○○"... ... .

Since they were kids Sou has always been Rikiya's "subordinate", and now that they are in the student council things haven't changed that much... or have they? When a freshman comes into play, jealousy and secret plans are put into action. But is he really interested in who he says?

From Friendship Scans

Ranze Etou is an adorable immortal girl with a vampire father and a werewolf mother who would throw things at each other when they get into childish fights. However, Ranze just wants to live like a normal girl and lead a normal life. Unfortunately, she is "blessed" with the power to turn into anything she bites. For example, if she accidentally bites a cake the wrong way, then she will turn into a cake. The only way to return to normal is to sneeze! Ranze is in love with Shun Makabe, who is a handsome human boy at school. However, a human girl (without much hair) named Youko also likes Shun, and she would do anything to reveal that Ranze is not a human!! Things got even more complicated when Ranze met Aaron, who is the prince of the Spirit World. Aaron fell in love with Ranze and first sight, and he would do whatever it takes to win her away from Shun... Tokimeki Tonight was one of the hottest mangas in Japan, and you sure don't want to miss this hilarious comedy!

Continuation of Saki and Jun's story. Related series: Koigokoro (Prequel)

1. Makuai Curtain Call

2. Ijiwaru no Susume

3. Koi no Owari wa, (After a Love Ends,)
We met by coincidence, but I want to see you again.

4. Monopolize Your Time

5. Tokimeku, Hajimete no.
Sumika and Hanano have just recently become lovers. In an attempt to get closer, Hanano invites her senpai/lover to her house for a sleepover. The two are nervous and conscious of their movements since they don't want their true intentions with the sleepover to be revealed.

6. Good Morning Eve

7. Sore wa, Ashita kara.

One day while walking home from school, he finds that someone has messed with his trash. His trash has been left behind because the different types of trash were mixed up. The perpetrator kept mixing up only Souya trash everyday, so one day Souya decides to lie and wait to catch this annoying criminal. That day, he finds that the perpetrator was actually the recently transferred classmate, Tokisaka Koyomi, and she reveals that she has come from the future to stop all environmentally friendly activity. Now, Souya and Tokisaka will have to live together and destroy the environment so that Tokisaka can go back to the future. [DrCoke]

From MangaHelpers:
Yasaka Tokiwa lives in an unusual time, and according to his dreams, it's about to become even stranger. He's been having a dream of a woman called Ri'in ever since the robot, who he calls Makina, came to his home. He and Makina attend the same school, where their other classmates include a secret ninja (Kusanagi Kanata) and a sorcerer (Yata Haruka).
When Tokiwa, the robot, the ninja, and the sorcerer rush to rescue the student council president from a demon, the boys find that they've all been having the same dream! What is going to happen to their world?

From Kokoro no Oasis:

With her little brother in a coma and no money to pay a doctor, Milan has no choice but to turn to Clock and Chrome, Time Traders who grant wishes in return for hours instead of dollars.

A club made to rehabilitate problem children through community service is in the area. That is the "Special Extracurricular Activity Club", nicknamed "Tokkabu"! A self-titled "Amateur Spy" who knows more about machines than anyone else and a childhood friend juvenile delinquent who prides herself in her crimes; together they should have begun their activities. However! Their president, Ninomiya Sawa, declares she wants to help the neighborhood as a hero! Little by little, the days of the gentle and passionate Trouble Buster begin.

A collection of short stories:

• Boketsu

• Taikutsu na Tsuki

• Johnny kara no Dengon

• Round Girl

• Nade-shiko

• Chinpa

• Jinsei Kaya no Soto (Kari)

From AnimeWaves:
Shindou just became a new investigator for Tokki: The Special Mobile Investigation Force. On the day of his graduation, he finally saw the half-naked girl that he had always saw in his dream in real life and finds out that she's part of Tokko: The Special Public Safety Task Force. Shindou ends up joining Tokko to avenge his parents' deaths, whose bodies were ripped into pieces...

Yamada's parents have gone abroad. Worried about him staying alone, they hired a maid to look after him. The problem is that the maid seems to be a delinquent who takes her job very seriously. Nothing will stay the same for Yamada anymore.