From Manga Abyss:

Hotaru managed to get in the same high school where Haruna-sensei teaches to see him again! However, on her first day there, she meets a very unpleasant guy who looks just like her beloved sensei...?

Hinomiya is a quiet student who never says anything, but has a supernatural power. He saved Shijiro Sayu a number of years ago when she was falling, and since then she has considered him a friend. One day, an unnatural murder occurs, and a little girl escaping the killers runs into Hinomiya and Shijiro, with the supernatural villains not far behind!

High-school student Sawatari has his usual customers and doesn't get emotional about it. So why is it that he always seems to let "that person" drag him around? a very short story.

When a female student is abducted and on the verge of being raped, Boogiepop rushes onto the scene just in time to save the day. But Boogiepop's new male alter-ego, Akimizuki Takaya, finds himself in the middle of a crime wave with ties going back to the previous owner of the Boogiepop mantle.

From Yaoi Is Life:

In Spring of his junior high 2nd year, Saitou got in the same class as Suzuki. Receiving Saitou's help while being bullied in first year, Suzuki smiled shyly while thinking, "what if we became friends". Saitou is becoming more and more conscious about Suzuki and their relationship starts to change?!

Including the continuation of Bokura ni Matsuwaru, etc. (You & Me, etc.), Bokura no Ashita no Houteishiki (The Equation to Our Future), and Sono Te Kara Tsutawaru (I Can Tell by Your Hand).

A slightly different telling of the hit manga " Boku wa Tomodachi ga Sukunai." It still follows the same concept as making a friend making club. If you enjoyed the original you probably will like this.

A collection of one shot stories from Takako Shimura, the author of Hourou Musuko and Sweet Blue Flowers. These stories deal with issues relating to gender, romance, ideals of beauty, and relationships with parents.

1. He said "I'm a girl"
2. Rakuen ni Ikou (Let's go to the Paradise)
3. Shounen no Musume (Boy's Daughter)
4. The Theme of Akemi ver. Teruo
5. The Theme of Akemi ver. Yoshio
6. The Theme of Akemi ver. Haruo

7. The Flower
Contains the Transient Son character Yuki.

8. Sweet 16
A short, bittersweet story in which a girl realizes she's in love with her tutor, who's in love with someone else. The other main plot point is the main character's dread of the upcoming school marathon.

Koyama Kei lost his mother when he was still in elementary school and never connected again with his distant, workaholic father. The only real light in his home life is his sister Moe: a bright college student who obviously adores him. But Kei has intimacy issues that even his sister can't pick up on.

At 15 years old, Kei's never been in love, but he has sex with anyone who shows him interest. While he's in someone else's arms, he can forget the void in his own life.

One day in late spring, Koyama discovers what's missing: a slightly spacey med-student named Fujii. Unfortunately, Fujii is his sister's boyfriend...

-DokiDoki

From ShoujoMagic:

Yori's attitude has changed. He and his twin sister, Iku, used to be inseparable as children, but lately Yori's been different -- eager to be apart from Iku. Iku worries that he hates her, but the truth is far more scandalous. Now, Yori would risk losing everything to have his little sister. Iku loves her big brother enough that she would never risk losing him, and so she'll do what it takes to keep them together... but Yori doesn't want to have her that way -- as a sister dedicated to her twin. Can Iku ever love Yori not as a brother but as a man?

Boku wa Imouto ni Koiwosuru received the Shogakukan Manga Award for shoujo manga in 2008.

Mitsuki's a high school freshman worried about her looks--or, at least, her "baby face". Until, that is, she enlists a little help from classmate Atsuki and her makeup kit. When Atsuki's finished, the transformation is complete--and breathtaking. It's also when the romantic adventures begin--a roller coaster ride of the heart that young and old are sure to enjoy.

There are 2 extra chapters in 1/2 Ceremony (1/2 series book 4).

In recent years, more and more girls are experiencing the development of "tertiary sexual characteristics" during the later years of their puberty -- that is, the rapid masculinization of a certain part of their external genitalia. Ooi Haruka is one such girl, who has until now kept the changes in her body a secret from everyone but her family. However, after an embarassing incident involving the guy she's been crushing on in a crowded train, she wakes up to discover herself at school, surrounded by a group of students calling themselves the "Bra Girls (Swing Girls)." And they know her secret!?

From Tokyopop:

An anthology of stories about ordinary high school guys and their relationships...or lack thereof. Boys Be...takes a look at the trials of love and loss from a refreshing point of view and often adds interesting insight into what a relationship is like from an average guys point of view!

From ]Nagareboshi Manga:

Hijiki (a girl with an unusual name) has just entered a new school, and on the way there she encounters a mysterious boy alongside a beautiful lake. Hijiki has some secrets of her own, and will this boy be able to listen to her silent pleas for help...?

From Storm in Heaven:
Takatou Masaki is the second youngest of four sons, and seemingly a delinquent by nature. His hot temper has put a wedge between himself and his strict father, gotten him kicked out of one school, and tossed him at a school notoriously horrible for the one thing he's truly good at, basketball. A chance encounter with the willful Yuuki Kanako may serve as a catalyst for change, as the indefinable connection she feels with him draws them together.

Note: Won the Shogakukan Manga Award in 1988.

Ooshima's best friend and girlfriend says they love each other. He should be angry, but all he thought was that he was interfering into their relationship. Kurosaki is the boy that befriends him and might also be the person to help mend Ooshima's heart.

N/A

From Attractive Fascinante:

As an elite Moral Order Committee President, Sakaguchi Chiaki, never told anyone about his secret. However, only Mizoguchi, one of the members, understood him. Sakaguchi's uncertainty stepped in before their term ended. Where is the borderline between friends and lovers? When their bodies touched, that borderline fused together with their feelings. When they met again later, would the borderline still exist?

From Shoujo Manga Maniac: Kojima Mitsu (aka Honey) is in high school, but she's so small that she looks like she's in elementary school! One day while she is is changing into a maid uniform for a school event (with not much success...the uniform is too big for her), she find a little bat blocked by the window and helps it. Suddenly an awesome guy appears in front of her! He is a vampire and as thanks for saving his "toy," he helps turn her into an adult (with a kiss)...

Based on Makoto Shinkai's film, Byousoku 5 Centimeter follows the life of Tohno Takaki, Shinozaki Akari, and Sumida Kanae. The manga follows the three and their different view points as they chronicle their way through life.

A collection of oneshots. Bye-Bye, Little: Ai is a first year high school student whose father passed away when she was still in elementary school. Her immature younger brother is a pain, she has to do all the housework and it's awkward being around her own friends. But Takahashi-kun is secretly supporting her in the shadows... a story about growing up. Love, Stupid, Me: Chie wishes that her boyfriend Satoshi would show her more affection, but she knows he doesn't like the clingy type. The fact that she's hated by Satoshi's friend Sugiyama Sei doesn't help. However, it turns out that he doesn't hate her after all... Doki Doki Miyuki's in love with Shuntaro, but she won't confess because she's afraid of ruining their relationship. But when another girl confesses to Shuntaro, something begins to change... Too Young: Mika's mom doesn't approve of her relationship with Yoshiyuki, her boyfriend. In fact, she doesn't approve of anything she does, whether it be losing piano contests or getting Bs on her tests. How far will she go to protect their love?