Kaede Yukimura is a gorgeous girl who has been challenging every person in her class to a shogi bout. If you win against her, she will confess to you publicly and go on a date with you. As more and more classmates lose against her, the reason behind her bet begins to unravel slowly...

SK8 is a story about 8 skaters who enter competitions to determine who is the best skater in Florida.

High-Schooler Tsukishima Satoru gets confessed to by local female High-School boxing-talent Saotome Yae. He rejects her initially because he does not want to impede her boxing career (and prevent getting beaten up by her fans).

Her female coach, Shioya hears about this and decides to install him as Saotome's trainer so that they can secretly date each other. This situation is also aided by his extensive boxing knowledge.

From MangaHelpers:

Not a lot of people know that one of the most talented and ruthless Mahjong players in the city is a young high school boy. Kei is a teenager of few words, but his observation skills, unwavering will and experience in the game allows him to survive in a world full of powerful, rich and dangerous characters.

Kei is currently hiding a girl named Amina who has entered the country illegally and protecting her from being deported. He spends his days sleeping through class and his nights playing high-stakes Mahjong, waiting for when a worthy opponent arrives. [vyc]

A new official spin-off of the popular weekly series Haikyuu!! In which our protagonists are the members of the rival schools. A comedy series about their ridiculous antics that you can't read in the original story!

DESTINED TO DANCE

Homely and shy, Himé is burdened by the name her mother gave her, “Princess.” Wanting nothing more than to be unnoticed and live a modest life, Himé gets a jolt of inspiration when she tries a dance class where she meets Tango. Her teacher/dance partner, Tango happens to also be her classmate at school. Unfortunately, Tango is desperate to keep his ballroom dancing a secret, believing it will ruin his cool image if anyone at school finds out. Will Tango quit teaching Himé in order to keep his secret or will he be the partner Himé believes he’s destined to be?

In Ome, a city in northern Tokyo, the adventures of four different characters of different mentality and cultural background will take place. The only common interest they share is their love for sports and parkour. The heroes are four children that destiny brought together to enable them not only to help each other but also to achieve their personal goals. Tension, competiveness, humour, friendship, intrigues and lots of parkour are the main elements of the world of R.u.N. Are you ready to Remember ur Nature?

From SRoMU: A lone boy standing on the beach. A loss of memories. The death of a great friend. A soccer club that had fallen apart. Mysteriously overwhelming skill. The name of the young man is Amakusa Kain. A new kind of feeling of soccer suspense begins here.

Everybody has a dream, and for Shou Kazamatsuri, that dream is simple: he wants to be the best soccer player he can possibly be. He's the spirited leader of the Josui Junior High team and everyone looks up to him. In turn, he tries to keep the team together at any cost!

Short but fun manga about a group of Magic: The Gathering players competing with each other.

You'll need a certain level of MTG knowledge to fully enjoy this manga, but it should be a blast for anyone who has played MTG or knows a bit about trading card games.

From Chibi Manga:

"That was the highest fever I never had. Because of those guys."

When I entered in high school I met the team of “tsubasa ga oka D.C” Those guy were so problematic but looked like Host! That’s what I thought at the beginning…
“…bet with us Alice, bet with us!”
“I’m going to ridicule you guys!”
“Let’s make a deal. If I lose, you’ll have my first kiss”
If it’s Takeru-kun, I can bet anything. I can give him every “first things” of my life.

Special one-shot by Yusei Matsui, creator of Assassination Classroom!

Super Yankee, Tendou Haruku, lives in the Ibaraki countryside. A lover of rebel yankee girls and MAX canned coffee, he is living peacefully... Until he meets the beautiful Sawa and the sport of ping pong. The beginning of a legend!

Your everyday, soon-to-be Junior High student Kinoshita Shinya is only visiting relatives when he gets lost. Your everyday sportsy karate kid Yanagiya Takumi is only going for a jog when he runs into Shinya...When losing one's way leads to finding one's passion, every turn brings new encounters, and a new friendship is born! Follow this amazing new series about Karate that is sure to excite!

Detailing the adventures of two friends interested in shakotan, the Japanese term for low riders.

Yuwen Jun (Cheng) came to Japan to get married because of childhood arrangement. Instead he got himself into a thrilling journey where kendo masters, detective sisters, young misses of rich families entangled with him. Yuwen Jun was stunned while facing so many unexpected incidents: "I just came to get married..."

The encounter between Itto Ippongi, a high schooler who blunders no matter what he does, and a road race bike.
Riding a bike might very well be the way for him to change himself.
Thinking he might actually be able to achieve something great,
Itto joins Team CycleOn which Subara Miyata, his classmate, is a member of...
A genuine cycling road race manga that will lit fire in your heart and make you want to go to the distant Alpe d'Huez has come!!

A spin-off of Doraemon, it is a story about how a baseball team comprised of futuristic robot cats and a human make their way towards becoming a great team. The author was an assistant to the author of the original Doraemon manga.

From HMR:
Once upon a time, there was a little girl. One day she played a trick on a drunk and made him angry. The drunk was going to hurt her, until a boy appeared and saved her. It's been eleven years since that incident, but Nonoka is still looking for the "prince" who saved her.
This manga's got a love triangle and lots of judo!

Ever since their champion was defeated, the world of girls' junior high ping pong has been in turmoil. Koyori is the new smirking transfer student at her junior high and she's ready to shake up girls' ping pong.