In the Mazinger Otome series:

V.1 - Mazinger Otome

V.2 - Mazinger Otome Taisen

The story starts with a seemingly unassuming class rep Adachi Hana who has taken an interest in the school's known delinquent, Shinagawa Daichi. Just what is her reason for following Daichi and wanting him to go on the class field trip?

Included in volume 11 is the story called Fairy Megane, a crossover between Fairy Tail and Yanki-kun to Megane-chan.

25-year-old Haduki-san has no experience in romance but ends up being pushed into a relationship by her younger sister. Her partner is a high-school boy!? A timid love story begins.

From Viz:

Yuji has just started a new semester of high school and everything seems to be normal. That all changes when a mysterious man named Friagne begins turning people into blue flames. And wouldn't you know it? Now he's after poor Yuji!
To the rescue comes a girl named Shana. But is she too late? As it turns out, young Yuji may already be dead. What the heck is going on?

A Spinoff of Senyuu.
A story of how Ros and Alba meet.

Sumire is a 17 year old high school girl who wants nothing more than to make friends with her new classmates. She's so disappointed that they all seem to hate her, calling her a pervert, a dirty old man, creepy, weirdo... alas, what is a poor life-sized puppet to do in this cruel world.

Katsuragi Keima is known on the net as the god of getting the girls while in real life he’s known as otamegane and he hates all real girls. However he is approached by Elsie, a devil from hell, to help her in catching runaway spirits that hide in people. Apparently the spirits only hide in the hearts of girls and the only way to get the souls out is by making the girl fall in love so the spirit gets forced out. And he’s not allowed to fail or he will lose his head.

From: Easy Going Scans

Our protagonist Jo Cheul-Hee is a delinquent who enjoys picking fights and aims to take control of his new school where he gets transferred, but what he doesn't know is that it's an all girls school.
Being the only male student there, everyone thinks he is gay!

On earth's last day the survivor is a hikkikomori?

A short romance one-shot about a boy being dumped by the girl he likes, his cousin, and a cough.

The anthology is a set of four-panel manga from the Toaru Majutsu no Index light novel creators Kazuma Kamachi and Kiyotaka Haimura and the A Certain Scientific Railgun spinoff manga creator Motoi Fuyukawa. Each Story is written and drawn by various other mangaka.Related:> To Aru Majutsu no Index (Main Story)(http://mangapark.com/search?q=to-aru-majutsu-no-index)> To Aru Kagaku no Railgun (Side Story)(http://mangapark.com/search?q=to-aru-kagaku-no-railgun)

From Nigihana: One day a high school student named Haruhiko who is aiming for Tokyo University has discovered a very important secret. From the closet, appeared a beautiful girl with a black pony tail, Utsuki who came from "Moon Village" with her Ninja Troop said to him, "It's been 7 years, master."

This year, the student council has decided to add an exciting new contribution to the school's culture festival; an Idol performance! However, they don't actually have the money to hire any real Idols, so someone's going to have to train up an idol group from their female classmates. Hirano Harufumi is that unlucky someone. He has no interest in Idols at all, but he must put together a performance or risk expulsion from the school for his failure.Not surprisingly, most high school girls are too embarrassed and self-conscious to dance and sing in front of their classmates in a skimpy outfit. When Harufumi tries to think about who he would like to see as an Idol, his thoughts are drawn to his cute, shy, clumsy childhood friend Aizawa Momoka. Will Harufumi be able to convince her to be an Idol before it's too late?Sequel:> Atashi no Idol ( http://mangapark.com/search?q=atashi-no-idol )

From here:

The basic story: a high-school student (Nanase Hokuto) living away from his parents (who are in Australia) shares an apartment house with three older girls. His exposure to their whimsical and teasing nature leaves him pretty much despising females. However, the high-school idol (Taniyama Maina) ends up having a crush on him. Her best friend is Nakajima Atsumi, your typical sukeban. Hokuto's best friend, Moriyama Syuuichirou, is the young-punk biker. These two friends conspire to hook Hokuto up with Maina, much to Maina's delight and Hokuto's chagrin. Into this setting we interject the jealousy of the rest of the high school, a female rival for Hokuto's attention, a number of fights, the inevitable parents recalling Hokuto, and Maina threatening to run away from home. We could go on, but pretty much everything is in here.

Kawaii Makoto is a 16 years old boy.He adores everything with heroes and dreams to become one.This is the story how he'll become one...

From Dan of Population GO:
An island was recently discovered off the coast of Japan. This island was mysteriously full of young men and women who lived as though they were in medieval Japan. The Japanese government immediately went to work enrolling them into modern Japanese schools. But not all is as it seems with these islanders. Could they all be descendents of the yokai expelled by the fabled Momotarou? Nahh, couldn't be.

A box that grants three wishes might seem like a dream come true.
At least that's what Keita thought, but inside the box he finds a girl. And this girl is no genie--Maki's a devil princess, and she's come to take Keita's soul! But she can only take his soul after he makes his third wish.
So, as a sheltered demon with little knowledge of how to be evil, Maki must rely on her trusty guidebook to teach herself the ways of the nefarious arts and trick Keita into using up his wishes. Until then, Maki's going to live with Keita until he can't stand living anymore.

Hanatori Suimei, a ronin, came to his aunt's house to study for the next university entrance exam. Turns out the place he will be living in is a kindergarten run by his aunt. There, he meets Aiko, a 4 year-old girl, Haru, a teacher there, and many other children. How will his relationship with Aiko and Haru turn out?

*Includes a side story called Same Sight in volume 1.

The newest IS spinoff that stars Charlotte! This monthly webcomic is sure to show you more of her life that hasn't been shown in the light novels nor the anime. With stories that is as sweet and enticing as its title, you'll be wanting for more. Be sure to not to miss out on this serialization about the ever adorable Charlotte, Ichika and the others!

After guiding the infamous Tokyo Kissho Academy through a crash-course of his unique brand of life-lessons, a battered and bruised Eikichi Onizuka takes a well-deserved trip to his hometown of sorts, a typically quiet surfers paradise called Shonan. Unfortunately, with child neglect and abuse becoming a global phenomenon the self-proclaimed GTO (Great Teacher Onizuka) quickly finds himself back in the saddle for what he hopes is a painless two-week long field trip with some teens in need. And while Onizuka's curriculum may not rely on the reading, writing and arithmetic that is common in most classrooms, he has more than a few good lessons in personal development, fisticuffs and fun to teach a new generation of trouble teens.