For high school girls there are some "battle days", for example Valentine's Day, Christmas, and...

Nishikaze to Taiyou (lit. The West Wind and the Sun) is a one-shot from Mashima Hiro, mangaka of Rave Master and Fairy Tail. The story follows treasure hunters Zephyr (西風) and Sol (太陽) as they search for a statue of a goddess atop a mountain. They find the statue, but suddenly, the statue comes to life...!

Track and field star Nimi, sees a boy molesting a girl on a train and he falls in love with her at first sight, as he get off the train he watches a baseball game where the girl is crying, her father is the coach of the team and the team is losing badly, he then swear to join the baseball team to make her happy, but there are obstacles one of her childhood friends is a extremely talented baseball player and loves her, and is always proposing to her and trying to make her his, and then there is another girl the ace of the track and field team who has fallen in love with Nimi when he was still doing track and field, and is trying to make him hers.

From Adachi's Universe:
We start with our main protagonist, Shichimi, bidding farewell as he readies for his journey into Edo (on our Earth, Edo was the old name of Tokyo before it became the capital of Japan). His mother has just died, only leaving him a walnut and a request for him to go to his half-siblings. Shichimi bids farewell to a sternly old man, who is a firefighter. We can tell this from the symbol on his cloak. This symbol is also on Shichimi's cloak. Upon reaching the town of Edo, Shichimi meets a mysterious man, who ridicules the peace of the world as an illusion.

After being awarded the Nobel Prize, child prodigy Alice T.P. Riida runs away from home and creates the first Artificial Human, Ninomae Shii. Along with Shiratori Jun and Kurosaki Yaoki, Shii now struggles to find out for what reason he was made for.

From Easy Going Scans:

Yun-lee is a girl who is carrying a huge emotional scar in her heart. Due to an accident, she lost 2 precious years of her life, the time period between 19 and 21 years old. Her life is empty. She is miserable, but still attending a preparatory school in an attempt to catch up with all the time she has lost. Suddenly, one day on her way to feed some stray cats, she comes across a young man who seems to have what she has lost... the period between 19 and 21 years old.

Marimo has a job to do... but it's too cold and she doesn't want to leave the kotatsu.

A special collaboration oneshot between Nisekoi and Haikyu!!

Adapted from cottonholic on nihonomaru:
Fujiwara is a man of unusual tastes—he finds plain-looking, borderline unattractive men appealing. And Karahashi, his lover and middle school teammate, has started to be insecure about this. What will he do to keep Fujiwara’s attention?

Continuation of story about a man and his old love that has become a hairdresser in Shiranai Kao.

Ai Nekomori can see the "doors" to people's hearts, meaning their thoughts. Therefore, he can't trust anyone and never opens his heart.. But then he meets the upbeat, tomboy Ritsu Sengoku, who says whatever she's thinking. Can she open his heart?

Nemoto, your average teenage airhead, has her highschool life flipped turned upside down when she accidentally volunteers to be class rep with the most serious guy in class! Can the two overcome their differences and become friends...or perhaps more?

Nineteenth century England... After her parents pass away, ten year old Coco inherits the title of "marquise" and the expectations that go along with it. Nidell, a young tutor, is hired to teach Coco, but quickly finds himself facing a past he's tried to hide.

Extremely negative Fujiwara-kun and overly positive Tachibana-kun are... a couple. While eating lunch hand-in-hand, they have their dates. In the midst of a bustling routine, this duo's carefree tale of love occurs--a small part of which is shared in this book.

A two-volumes sequel of the Nodame Cantabile series. Chiaki and Nodame are back in Japan, Nodame for her first recital there, and Chiaki for his first Opera Concerto.Prequel:> Nodame Cantabile(http://mangapark.com/search?q=nodame-cantabile)

From Storm in Heaven:

1)You Blossom in the Summer
Shinobu grew up in a town so small that he didn't even have any classmates in elementary school. Without any friends his age, he spent his time learning about flowers with a local horticulture expert. Now that he's moved away to a city, he still sticks to himself, since he never really learned how to make friends. That is, with the exception of Yukihito, who came up to him one day and became his friend. The trouble is, now Yukihito means the world to Shinobu, and he doesn't know what to do about it.

2)The Language of Flowers

3)The Insightful Florists

4)Strawberry Concerto

5)Cafeteria Love

6)Thermidor Fireworks

Short stories all related through a common medium: Eggplant.

Teppei Arima is a second-year high school student who lost both of his parents in a traffic accident on their way home from a family trip. His grandfather, Isshin Arima, happens to wield the puppet strings in Japan’s vast economy and demands that Teppei becomes his successor as the head of the Arima Group. To prepare for his debut into high society, Teppei enrolls in an elite academy for the scions of the rich and powerful.

Based on the fake manga in Bakuman (http://mangapark.com/search?q=bakuman) it is a one shot of Otter no.11.

From whyanime:

This series is about a girl named Otome who's 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 three 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?

Extra 1 - The Boy Next Door (Tonari no Danshi)
Extra 2 - System vs Freedom

Mizuho can't believe his ears when Grandpa's will is read out. Grandpa's final wish is for Mizuho to attend the same academy as Mizuho's mother. The catch is it's an all-girls school. With the help of his friend Mariya however, he gets a makeover good enough to fool everyone at the academy.