From Nekohana:
Rich young Master comes across a girl alone and abandoned during Christmas. He decides to take her in and name her "Mike". Now he's in high school and she's his personal maid. Did I mention she now loves him and he's rather sadistic with a terrible panty fetish?

From FORTE ATROX: Kang Yurhan is handsome, rich, a little dense, and above all else lucky! But that all changes when his father's company is forced into bankruptcy. Homeless and friendless, he doesn't have a choice but to sell himself to Miss Chunja, a famous fortune teller who seems to have some plans for the poor young man...

Almost two years have passed since Ryousuke made his wish to become a beautiful girl. Although he continuously and faithfully tended the plant that was supposed to make this seemingly impossible transformation a reality, the miracle has yet to happen! To what lengths will Ryousuke go in order to make Gunma fall in love with him? Is it possible that Gunma might actually return Ryousuke’s feelings…!?

Konatsu's dream is to become a movie director. She falls in love with a popular actor, Aoi Nonomiya, and decides to confess to him upon her friends' encouragement. But...

From Taciturnity Scans:

Second-year middle school student Ayumu Kurihara changes classes and is seated next to the beautiful but strange Misuzu Tsukishima who dislikes boys. Misuzu can't get close to other people, but after being moved by Ayumu's sweet, honest personality she begins to open up to her little by little. Ayumu too is captivated by the awkwardly delicate Misuzu and the two of them become close.

V.3 (a.k.a. Second Season)
It's Shimizu Kanako's first day at an all-girls high school, and she's a little overwhelmed. Hoping to make new friends, she bumps into the odd and distant Kamei Ao, as well as her first three new friends: Aki, Rikako and Haruna. Of course, not all can be so sweet in the world of girls.

Anna entered the same high school as the person she loved. But that person is in fact her cousin, Reiji. While continuing to conceal her feelings for him, she begins to suspect that Reiji is love with Rumi, her best friend. But what is Rumi's real secret...?

From JShoujo Scans:
After three years Mimi comes back to the island where she had spent her childhood. She is greeted by her childhood friends Yousuke, Sumire and Hikari. Heartbroken in Tokyo, she has now came back to the beautiful island surrounded by the deep blue sea.
But among this four friends, friendship soon turns to love? A blue world spreads before your eyes, an unforgettable story begins.

This is the story about a girl who was named Lily by her grandfather, who hates her name because it becomes a laughing and teasing matter. Her grandfather passes away, and she comes to disbelieve miracles. One day she meets Abe, a guy who once knew her grandpa and, thanks to him and to her grandfather she learns to like her beautiful name and realizes the world is full of miracles.

Chopin and Liszt - both great composers, friends, and rivals. Liszt, after Chopin's death, Liszt remembers their meeting, their friendship, their lives together, and the music they made.

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...?

Asuka swore she'd leave the night life behind when her brother's job moved them to a new city...after all, it's hard to be a cat-burglar when you live with a detective! Despite her determination to move on, her talent for thievery hasn't gone unnoticed, and it seems her secret identity is not so secret! Approached and asked to join the group of chivalrous vigilante thieves taking the underworld by storm, Asuka has no choice but to accept...but can she keep her brother off her case?

A boy whose father fell prey to a book which drives its readers to take their own lives, a girl who tries to protect the boy from meeting a similar fate, a forensic pathologist who cannot forgive herself for the death of a girlhood friend, a mysterious used-book store - The Book Club - that only deals with books about death and despair, and a suicide which was committed in the ancient Library of Alexandria are all inexplicably connected in this unusual Korean horror story.

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).

A collection of six short stories:

1. Blue Moon Lovers
Blue moon... a phenomenon so rare, it's almost a miracle... Without thinking, Yuri tells the super cool bartender Rukia that she's fallen for him at first sight. Rukia rejects Yuri outright, but that's not enough to make her give up...
- From Sunny Side Up Blog

2. Karefechi

3. Koi Shoku Neiru

4. Kodou ni Kiss shite

5. Ikenai Kareshi

6. Boyish na Kanojo
Ayame, a popular idol who looks like an Ikemen but is actually female, has to claim she has no lover. In actuality however, she is going out with a regular guy, Nanase. But keeping both her idol status and love life in harmony may be harder then she expected...
- From Intercross

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.

From Anime-tion Scanlation:

At age 17, Nana still doesn't have a boyfriend. One day, she went to the beach and met with a cool guy. They exchanged numbers and texted but the cool guy turns out to be her younger brother's friend who's 5 years younger?!

From Storm in Heaven:

Whatever Ozu Hayato was expecting when he went to his late grandfather's house for the reading of the last will and testament, it wasn't for his grandfather's old hat to fall on his head and allow him to see the ghost of a long-dead girl. Nor was it to inherit an entire office building, complete with a members-only hat shop. And who exactly is that man responsible for carrying out the terms of the will, and how does he know about the hat? And what's it all have to do with Hayato, anyway?

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)...