For as long as she's been aware, the heroine, without a single relative, lived under the care of the state. Both of her parents' faces were unknown to her.

In front of this heroine, a boy appeared.

The boy's name was "Hikaru." It appeared that he was the heroine's twin brother, separated at birth. He had a proposal for the heroine: "Could you go to school in my place?"

The heroine was shocked by this crazy suggestion.

Furthermore this was an all-boys schoolthe only high school in the prefecture for delinquents.

From MangaHelpers:
Mikado Shuuji is just an ordinary guy, but he has a very unusual knife that he uses for cooking. It's actually a famous short sword that marks its owner as the head of the ninjas, and now there are hot ninja girls coming after him to take it back. Hinamori Botan is one of those hot ninja girls, but her efforts to attack Shuuji mostly end up inadvertently stripping her. After she concludes that she does not want to steal the sword and kill Shuuji, she ends up deciding to serve him as a ninja instead. Now she must protect him from the other ninja that come to claim his sword and his life.

Outer space, the far future.

A lone seed ship, the Sidonia, plies the void, ten centuries since the obliteration of the solar system. The massive, nearly indestructible, yet barely sentient alien life forms that destroyed humanity’s home world continue to pose an existential threat.

Nagate Tanikaze has only known life in the vessel’s bowels deep below the sparkling strata where humans have achieved photosynthesis and new genders. Not long after he emerges from the Underground, however, the youth is bequeathed a treasured legacy by the spaceship’s coolheaded female captain.

Note: Won the Kodansha Manga Award for general manga in 2015. Won the Seiun Award for Best Comic in 2016.

It is a manga of high-school baseball. The main character, who starts as pitcher from a country middle school, gets teamed up with a catcher from a school with an elite baseball team. He decides to leave the countryside to attend the school that this catcher plays for...

Winner of the 53rd Annual Shogakukan Manga Award (2007) and the 34th Annual Kodansha Manga Award (2010) for the Shounen category.

Tadayasu Sawaki has just enrolled in an agricultural university in Tokyo with his long-time friend Kei Yuuki. Although not known outside a close circle of friends and family, Tadayasu has the unique ability to see and communicate with microbes, which appear larger and look different to him than they do to a normal person's eyes. This catches the attention of Keizou Itsuki, a professor at the university and an old friend of Tadayasu's grandfather who specializes in microbiology and fermentation. Thus begins Tadayasu's tutelage under Professor Itsuki, aided by his graduate student Haruka Hasegawa, as he attempts to adjust to his new life at the university.

Note: Nominated for the 1st Manga Taisho in 2008. Won the Grand Prize for the 12th Tezuka Osamu Cultural Prize and the 2008 Kodansha Manga Award for general manga. Won the Seiun Award for Best Comic in 2015.

Utsunomiya Sousuke is dead. But his new life is about to begin...in Hell! Upon awakening in the Afterlife, Sousuke meets his painfully sexy devil guide Sanagi, who may be short of stature, but packs an all-powerful punch. Like Rintaro before him, can the hopelessly irreverent Sousuke repent from his sins, or is he fated to be forever tortured and teased by a gorgeous demonic temptress?

A sitcom about an ordinary man and his alien wife.

From Baka-Tsuki:
Tada Banri, a newly admitted college student at a private law school in Tokyo, found himself completely lost after the opening ceremony, trying to find his way to the freshman orientation. At that moment, he ran into another lost freshman from the same school, Yanagisawa Mitsuo, and they hit it off at once.

Somehow arriving at their intended goal just on time, there appeared in front of the two a beautiful girl holding a bouquet of roses. The girl then whacked Mitsuo across the face with the bouquet and handed the flowers over to him. “Freshman, congratulations”, was all she said, and then she left.

The stylish, well dressed, perfect woman that had swung at Mitsuo was his childhood friend, Kaga Kouko. As children they had promised to marry each other one day, fulfilling their dreams. In order to escape from her, Mitsuo had gone out secretly and taken the examination for this well known private college, but now she showed up in the freshman orientation hall. She too had taken the law school entrance examination, catching up with him there.

Mozu Sousuke is fired from his job as an model and half-forced to move to a farm in Hokkaido. As someone who's always lived in the city, the shift in schedules, the heavy labour, the lack of contact with the outside world, the cold, the temperamental livestock, and the rather fierce little sister are quite the ordeal.

Three strangers ally with each other to survive a Battle Royale style game of death on a deserted island against other contenders. A lot of contestants have amnesia and each person has a life sustaining bracelet which heals wounds over time.

Made for promotion of game 'black survival'.

Serinuma Kae is a chubby second-year high schooler and an avid fujoshi who secretly ships her classmates, Igarashi-kun and Nanashima-kun. The death of her favorite anime character causes her to become stressed and lose weight rapidly. Now that Serinuma has become an attractive girl to her classmates, her snarky kouhai Shinomiya-kun, and her senpai Mutsumi-senpai. How is she going to deal with them...with her constant BL-filled, fujoshi mind?!

Won the 40th Kodansha Manga Award for Shoujo in 2016.

Despite his short stature and his cowardly personality, Eisaku Yazawa dreams of one day becoming a gang leader of a nation of thugs. As he starts high school, he ends up meeting several delinquents who attend the same school as him.

Won the 23rd Kodansha Manga Award for Shounen in 1999.

Moonbeard is a comic in which characters interact with each other inside tiny boxes. Don't they know there's a whole world out there?

From Divine Sanctuary:
Megu is in love with Funaki-senpai, the object of admiration of all the girls in school. However, she can only look at him from afar. One day, Megu happened to pick up Funaki-senpai's underwear!!! Will this give Megu a chance to get closer to the guy of her dream?

The story takes place in a world after the legendary warrior defeats the demon lord. After he brought the peace to the world, he decides to set out on another adventure to search for a wife.

Kazuki Atake is a young boy who has a feeling for Midori the girl from the next class but what will happen if the girl he likes is his rival in the other side...?