Collection of short stories:

1. Sensei wa Sadistic (Sadistic Teacher)
Refusing numerous confessions, Tamami's nickname is "Princess that's difficult to fall". In reality, she's inexperienced in a love relationship. One day, in order to refuse a confession, she mentions "I love Kunugi, the math teacher." and lies. Kunugi overheard this conversation and....?!
-Chibi Manga

2. Sensei wa Usotsuki

3. Santa Claus Panic!!
It's the season of Christmas and companies are advertising their services more determinedly during these times. Yayuka accidentally picked up a flier saying a Santa will give her a wonderful gift on Christmas if she calls that number. Not wanting to be alone of Christmas, she calls the number and prepares a Christmas feast for Santa but when the doorbell rang, there stood a very young and handsome Santa who happens to be a debonair host!
- Aerandria Scans

4. Renai Shisuu 0%

5. Sensei wa Yappari Usotsuki

From An Endless Story:

After the death of her father, Sakura decides to follow her father's last wishes and move into Sakura Dormitory and attend Sakura High. However, on her way there, she's approached by a stranger who mistakens her for someone else and steals her first kiss!

From Nagareboshi Manga:

The student council is full of strange, quirky people with clashing personalities. One person in particular, Tsubaki Kiyoi (nicknamed Tsubakiyo), has a special talent that only one other person knows about-- when she touches someone, she can access their thoughts and memories. But because of this talent, she is very introverted and damaged inside. Can she overcome her fear of coming in contact with other humans, and take control of her power?

In search of her mother Nagi, a girl from a desolate country village, comes to a big city and enters Swimming Suieikyou High School. Shortly after joining the swimming club, Nagi finds out that the pool is actually completely overtaken by boys! But in this never-practicing so-called swimming club Nagi finds something...

4 Stories---The first and second story have the same heroine.

She works at a daycare center or kindergarten, and unknown to her colleagues she used to be a much feared female gang leader. ^-^ Also, the heroine has good vibes about a certain male colleague. One fine day, she meets an ex-male gang leader who knows her past...and events start unraveling from there.

For the second story, it's set in the daycare/kindergarten too. The main character is one of the kids in the kindergarten, and he has a secret which he is afraid to let other people know, especially his beloved teacher. (The heroine is his beloved teacher.)

Story #3
The main heroine is a 16 year-old girl. Her father is a scientist and always invents some weird things. What's more, he claims that he came from another planet! All these drive the poor heroine crazy ^-^ But at least now her love life is going fine...until the day 2 guys from outer space land on Earth, wanting to find out more about the 'Love disease'! Perhaps her father has not been lying after all?

Shizuka, age 17, was raised by her mother, and the two are very close. However, the store her mom's worked hard to maintain was swindled by the Sakurasei Real Estate Company.
Shizuka then, pretending to be the new wife of the president of Sakurasei, enters the Sakurasei family home while the president is away on business to get back the deed to her mom's store. In an instant she becomes "mom" to three boys, and the eldest son Kanon is the same age as her...

From Enchantment Scans]: Zhui-Ming (Shina in original) is just an average girl. However, due to a makeover, she accidentally gets mistaken for popular idol, Ai, by another famous idol, You. What's this? Ai and You are supposed to be dating?What is going to happen to Zhui-ming? (found in the series Panic x Panic )

From ShoujoMagic:

All Kumiko wants is to become a teacher; however her father is dead set against it. He is giving her one chance to prove herself as a teacher before forbidding her from pursuing this career forever. Meet her newest student, Ryu-kun. He has NO desire to LEARN anything from his tutors, rather he is an expert at teaching THEM about...SEX?!

Note: The story was originally released as a single short story, but it later became a series.

From Viz:
Hime Kino's dream is to one day perform voice acting like her hero, Sakura Aoyama, from the Lovely Blazer anime. So getting accepted to the prestigious Hiragi Academy's voice actor department is the first step in the right direction! But on her first day of class she meets Sakura's grouchy son, Senri, who tells Hime that her voice is awful and Lovely Blazers is stupid. Hime will not let that stand unchallenged. She'll show everyone that she IS a voice-acting princess, whether they like it or not!!

Nagisa and her beautiful, intelligent best friend Yumi couldn’t be more different. Of course, her childhood friend, Ryou, is always happy to point this out whenever he can. When Yumi gets a crush on the equally intelligent and handsome Kei, Nagisa is determined to get the two of them together like any good best friend would, but it seems that Kei likes Nagisa’s outgoing personality more than Yumi’s shy one. And where does Ryou’s crush on Nagisa–and the one she may have on him–fit into all of this?

Shiina Momose doesn't believe in fortune telling and the occult, but for some reason, she can destroy anything with a touch. One day while on her way to school, a young man approaches her and claims to be a God. Furthermore, he believes that he was guided towards her and for that reason he has become convinced that she should become his first follower! Naturally, Momose refuses; but when strange things began to happen... she can not do something about it!

As a descendent of the famous exorcist, Abe no Seimei, Yuuichirou has always been able to see ghosts. Yuuichirou, as a child, was proud to be a son of the Seimei Shrine and wanted to follow in his father's shoes and become an exorcist until he's bullied by Ishida in elementary school. Now, as a teenager, Yuuichirou has lost his faith in Seimei. Can a visit from Abe no Seimei, himself, restore Yuuichirou's faith and close the rift between father and son?

Talentless, shy Tsubasa has just been accepted into the prestigious Seiko Academy. He soon gets mixed up with the most popular kids in school -- and the entertainment world! Forced to join the pop idol group RINX as their lead FEMALE singer, Tsubasa soon finds himself stuck in the middle of a cross-dressing comedy full of mistaken identities, blackmail, and kidnapping!

4-koma manga based on Peach-Pit's Shugo Chara! manga. However, this one is being done by the mangaka, Kinomin.

From Del Rey:

Everybody at Seiyo Elementary thinks that stylish and super cool Amu has it all: But nobody knows the real Amu, a shy girl who wishes she had the courage to truly be herself. Changing Amu's life is going to take more than wishes and dreams - it's going to take a little magic!
One morning, Amu finds a surprise in her bed: three strange little eggs. Each egg contains a Guardian Character, an angel-like being who can give her the power to be someone new. With the help of her Guardian Characters, Amu is about to discover that her true self is even more amazing than she ever dreamed.

Contains the side story Shugo Chara! Encore! in volume 12.

Shugo Chara! was awarded the 2008 Kodansha Manga Award for best children's manga.

Midori Yamate is a 15 year-old girl and is very much a tomboy. When she was young, Midori meets a boy called Tsukasa Hino, who came to the island she lives on for a holiday. He teaches her to play soccer and she falls in love with the sport. Midori is inspired by Tsukasa and continues to play soccer in hopes that they would meet again someday. When they do meet again Tsukasa does something unforgivable. Determined to defeat Tsukasa on the soccer field Midori enrolls in an all boy high school.

Contains a short story of 2 chapters called Shounen x Cinderella in the 8th and 9th Volumes:
Sakuragi Azuma has a secret that no one should ever know about: he's actually Momo Kasuka, an up and coming female model! While shooting a new drama, he meets another arising newcomer named Yui Hazuki, and things are going to get heated!

Even though she loves singing, due to fear of her older brother's disapproval, all Nonoko Sugisaki can do today is wish on a shooting star. But then, Kenji and Mikki, who hear Nonoko singing, decide to ask her to join their band...?

Higuchi Asuka's mother dies shortly after she tells her teenage daughter who her father is. Only knowing the family name “Sudou”, Asuka goes in search to find her absent father.

On her journey, she finds a guy being rather rough with a younger girl. Unable to resist, Asuka steps in by battering the guy with her motorcycle. When she discovers it was a big misunderstanding (Manato was just trying to get his sister Kazusa to go home), she drives them back to their house.

Once there, Asuka finds out that Manato and Kazusa are the Sudou family she's been looking for, but the father isn't there, not to mention their mother also being dead since long ago. With no other leads, Asuka decides to move in as Neesan (the big sister) until their father shows up. Things get tricky when love builds within the complex family relationship...

Oneshot in the last volume: Otome no Jijou

From Manga Art:
After Daa! Daa! Daa!, Ruu is now a cheerful youth living in his home, Planet Otto. Then, a confused girl named Miu arrives through a wormhole from Earth. Ruu joins up with her and promises to take her home. Unknown to Ruu, Miu is the daughter of the same people who took good care of him in his stay on Earth.

Chapter 1-2: Suki♥Doki Tomita Emi falls in love with a player. How can she cope with him having so many girls? Chapter 3: Koibana - The Ex-boyfriend (story by YOSHI) Maho has an ex-boyfriend she just can't forget about. After being dumped, Maho started drinking and constantly sleeping only with men who ride motorcycles and look remotely similar to her ex, hurting herself in the end. Can Shunsuke, her best guy friend, help her out of this habit? (Baka-Updates Manga)