From Sugar-Oasis:
Nonomiya En, previously expelled from her old school following three suspensions, is forced by her father to enter Bijinzaka, a prestigious all-girls' high school where they train girls to become young, well-mannered ladies. Upon her arrival, En realizes that this school is definitely not for her and sneaks out. On her way out, she meets Narushima Chihiro, 1st year student at Jouyama Boys' High, on the other side of the hill.

Two bold and daring high school girls, Naomi and Jennifer have no enemies! They must certainly have many perverted stories to tell...or so you'd think. But they are actually pure virgins! The two finally get boyfriends, and their hearts beat fast as they look forward to their first sexual experiences, but!? (Source: ShoujoMagic)

From StarryHeaven:
Boys are silly, sex-hungry, and naughty. This book studies boys, living creatures totally different from girls, in detail, to answer questions about boys and their behaviors.

Otome, a girl whose searching for love now that she has entered high school. But of course, finding love isn't going to be easy, especially if you have 3 delinquent boys who are your childhood friends. Otome explains to the boys that since they are in high school now, she wants to find love and fall deeply in love, but Tokio (one of her childhood friends) insist that she be part of his plan. He dreams of taking over the school and becoming a grand gang leader; he'll even let her join as the sub-leader.What is she going to do? As she sneaks away from the boys, she catches a couple of girls watching the most popular boy, Touyou, being confessed to!!?? Is this love at first sight!? She decides to spy/stalk him...what will she find out??

Adventurist parents left three Ugajin sisters alone in the house and now they are living in freedom paradise! But their parents adventure financer wants the sisters to protect the peace in Manten Academy from the shadows. This is the stormy stage as curtain opens. First volume of Mayumi Yokoyama high-tension school love comedy.
From Manga Rebels

From blancmange:

Hanazono Eve is a woman in search for the perfect suitor. However, because of her family's influence, she believes that only rich men are worth marrying. But, what will happen when she enters the school that just became co-ed recently?

Satoshi and Satomi are childhood friends who have been trying to outdo each other in everything since they were small. Christmas is coming, and they’ve started a new challenge to see who can get a date for Christmas first! It seems that Satoshi might win the bet, with Natsuki-chan, the Sexy Dynamite of the class making the move and asking him to be her date, but will things be that simple for our plain-looking Satoshi?

Satoshi and Satomi are childhood friends and for a long time, they have been trying to see who is better than the other. Christmas approaches and they've decided to start a new challenge. The challenge is to see who can get a date for Christmas first. Satoshi's target is Natuski-chan A.K.A Sexy Dynamite. Will Satoshi get a date first, or will Satomi beat him to it?

From Operation Boredom :

Yamato Onidzuka. Childhood bully, punk, and sports prodigy. His old childhood friends are terrified of him, as he used to bully and harass them on a daily basis. When he transferred to a special sport's school, it seemed like his friends' worst nightmare had finally come to an end. But now that he's back, it seems like the nightmare has returned. Join Megu, Yamato, and their 4 other friends on their hilarious roller-coaster ride known as High School!

These stories about 4 typical high school girls' love life are Yokoyama Mayumi first work.
Story 1: A Real World
After 2 years Eri gets back together with her ex-boyfriend.
Story 2: Lip Lock
Nina made him break his "right hand" so she tries to make it up to him by being his right hand.
Story 3: That Is My Weak Point
Risa's ex-boyfriend stole embarrassing photos of her, and now she wants to get them back.
Story 4: Hotel Red Peacock
With the current course of events, Chika needs to make her bad tasting Love Hotel prosper.

-- Manga Rebels

Minami-sensei is a new teacher working at a co-ed school. She's unreliable in that she's the type to get into a fight with a delinquent that she had been scolding, but that's when a strange conspicuous guy appears and saves her. It turns out that this guy is the head of the school cafeteria and that there's a lot more to him than meets the eye... With him out to win her affections, will Minami-sensei be able to become a respected teacher?

(Source: Clairparfait)