From Tenshi-Tachi:

Takuma and Mayu's story began when they were only 8 years old. During his childhood, Takuma was constantly hospitalised due to his heart condition. He soon became friends with Mayu, the daughter of the doctor in charge of his case. Day by day they grew closer and closer. However, the summer when Takuma was 8, he made a promise to Mayu that he couldn't keep... Their story unfolds as they grow older and their bond gets stronger...

This manga received the 53rd Shogakukan Manga Award for shoujo manga.

Extras:

• V.01 - Motto Ikitai...
There is a ghost looming in a hospital. Two little kids, Mayu and Takumi, are now scared after listening to the ghost story from a nurse. Was the story told by the nurse true or not? The kids decide to find out.

• V.07 - The Things I Want

• V.11 - Kare wa Ike mo Shinai Sarukoen wo Mezasu

Machida-kun seems like the perfect brother, son, and student because he loves people. Helpful when he needs to be, but puts himself down when he feels like a total failure. However, the people that surround his daily life are there as a reminder as why Machida-kun needs no improvements because the people love Machida.

Note: Nominated for the 9th Manga Taisho Award in 2016.
Won the New Creator Prize at Tezuka Osamu Cultural Prize awards in 2016.

From Hanashi:

The start of high school life. To the girls, that also meant the start of their love lives. For brand new first year student, Takahashi Nanami (Nana for short), it was no different... She happens to end up in the same class as the incredibly popular Yano Motoharu, who rumors say that two thirds of all the girls are guaranteed to fall in love with. But will that hold true for Nana, who says that if she had to choose between like or dislike, she'd say she dislikes him!?

Note: Won the Shogakukan Manga Award for shoujo in 2005.

In a certain forest lives the adorable sea otter, Bonobono, and his father. These are the tales of his daily life and simple, comedic adventures with the other forest residents like a girlish chipmunk, a lazy fishing cat, and a bully raccoon.

Won the 12th Kodansha Manga Award for general manga in 1988 (shared with Be-Bop High School).

Hachimitsu Private Academy was a revered and elite all-girls’ boarding school on the outskirts of Tokyo…once upon a time. But with the new school year comes a revision to school policy: Boys are to be admitted into the student body for the first time ever. But on his first day at Hachimitsu, Kiyoshi Fujino discovers that he’s one of only five boys enrolled at the school. Their numbers overwhelmed by the thousand girls in the student body, is it heaven or hell that awaits these five (un)fortunates?!

Note: Was one of two winners of the Best General Manga award alongside Gurazeni at the 37th Kodansha Manga Award in 2013.

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.

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.

Tsugumi Rinko can’t wait to escape the tedium of high school for the challenges and rewards that accompany life at a fine arts college. She only has two problems: 1) She has few social skills and fewer friends. 2) With less than nine months remaining before her crucial admissions test, she has no practical art experience. Winner of 2011 New Face Award at 2011 Japan Media Arts Festival Awards.FYI: No demographic should be listed. Originally serialized in-app and NOT in a magazine of any type.

This award-winning classic story focuses on Marlee, an agent of the space empire sent on a mission to track down the opera singer Eroccus. There are three intertwining narratives which span planets and hurl the readers back 30,000 years in time. The narrative takes place in a non-linear fashion, unfolding across space and time, before folding back upon itself at its culmination.

Note: Winner of the Seiun Award in 1983.

Note 2: Gin no Sankaku was not serialized in a manga magazine. Based on content, it could be considered either seinen or josei.

The manga and the movies of the same name are both based on the Onmyouji novels by well known Japanese science fiction writer Yumemakura Baku.
All three concern the adventures of Abe no Seimei, an onmyouji (magician) serving the imperial court during the Heian period and his friend nobleman Minamoto no Hiromasa. Both men are historical figures who appear in various sets of tales. Many of the early chapters of the manga closely follow stories in the Konjaku Monogatari or Uji Shui Monogatari.

Note: Won the Tezuka Osamu Cultural Grand Prize in 1997 and the Seiun Award for best comic of the year in 2006.

A butcher with a dark secret finds a little girl.

Oneshot that was included in Afternoon’s 2012 Four Seasons Award anthology (v28).

From Viz:
Winner of the 2002 Academy Award for Best Animated feature, Spirited Away tells the story of 10-year-old Chihiro, a girl in the midst of a move to the suburbs who wanders into a strange town and finds a world of spirits ruled over by the mysterious Yubaba.

From Viz:

After her parents divorce, Anna Uekusa and her mother move from Tokyo to rural Shimane. Used to the anonymity of city living, An can't get used to the almost overbearing kindness of the people in her mother's hometown. But when personal tragedy strikes, An discovers how much she needs that kindness.

Note: Won the 50th Shogakukan Manga Award for shōjo manga in 2005 and was adapted into a movie in 2008.

On a remote island, a skilled swordsman who honed his craft on the local population attempts to atone for his sins and lift a curse by hunting and killing demons.

Winner of the Hagio Moto Special Award for manga.

Part 1: Hiroshima, 1955. Ten years after the city was consumed by a scorching flash of light, a woman's soul is still deeply shaken by the earth-shattering explosion that devastated her home and changed her life forever.
A family from Hiroshima struggles to come to terms with their survival of the atomic bombing of their city. The protagonist is Minami Hirano, about 20 years of age.
Part 2: Set some decades later, the niece of Minami Hirano is bewildered by her father's mysterious disappearances. She and a friend follow him to discover what he is doing.
The main theme of this is historic manga concerns the question what impact the war and the atomic bombing had on the most vulnerable. Fumiyo Kôno examines this question in her outstanding book- an award-winning, widely-discussed masterpiece.

Note: Won the 2004 Japan Media Arts Festival's Grand Prize for manga and the Tezuka Osamu Creative Award in 2005.

A sudden advent of an enigmatic creature pushes the world and our young heroine, Yuki, into the realm of the surreal.

Winner of the Grand Prix Award in Kodansha's AFTERNOON SHIKI.

From Del Rey:
By the order of Shogun Ieyasu Tokugawa, ten ninja from the Iga and the Kouga clans must fight to the death in order to determine who will be the next Tokugawa Shogun, with the surviving clan ruling for the next thousand years. But Oboro of the Iga clan and Gennosuke of the Kouga clan have fallen deeply in love. Now these star-crossed lovers have been pitted against each other. Can their romance conquer a centuries-old rivalry? Or is their love destined to end in death?

Note: Won the Kodansha Manga Award in the category "Best General Manga" in 2004.