In the Kokoro series:

Vol.1 - Otokogokoro (A Man's Heart)

1 & 2. Otokogokoro & Otonagokoro
Salary man Saki almost makes it home but passes out from fever just as college student Shinomiya passes by. When Saki comes to he realizes he's in a strange apartment and Shinomiya has been taking care of him for the past two days! Not wanting to be indebted, Saki tries to repay him as thanks but Shinomiya's having nothing of it. Luckily, Saki's pretty creative when coming up with a way to express his gratitude that has them both wanting more...

3-4. Kiss Kiss Kiss

5. Nibukoi (Dull Love)

6. Hiiragi-senpai no Koi no Ohanashi

7. W Pure

Vol.2 - Koibitogokoro (Heart of Lover)

Vol.3 - Koigokoro (Heart of Love)

Vol.4 - Tokimekigokoro (Heart of Excitement)

The number of chapters comprising the main story in each book is as follows:
Otokogokoro (2 chapters),
Koibitogokoro (6 chapters + omake) entire book,
Koigokoro (2 chapters + omake), and
Tokimekigokoro (5 chapters + extras) entire book.

1) Koi wa Itsumo Tabekake
Girls who don't treat other girls well are pitiful indeed. Also, they're not consider charming at all. Sometimes they tend to show their kindness in a wrong way. You won't be able to catch anything unless your bait isn't tasty. You have to scatter it well...

3) Forgotten Things in August
Red candyapple. Fireworks, a broken sandal strap. Since then ...

From Aerandria Scans

At that time, it was a crime for young girls to love...Set in the Taisho era, this is a story about the forbidden love between a young girl and a student.
Tamaki is the only daughter of a wealthy family, but she's been lonely since she was small, because her parents do not care about her at all. One day, Kuroda Kageaki came to her house as a student. Gradually, Tamaki started to harbor a liking for him. And yet her mother, Satoko, caused harm to Kageaki...!? Hidden there is a dreadful past! This is a sad and painful love story set in the Taisho era.

Included is the oneshot Rakuyouju to Koi no Hana.

A manga that details the meeting and formation of the idol group TRIGGER, rivals of IDOLiSH7. The three move beyond rocky first impressions and clashing personalities to form a group that is truly first-class.

From Girls' Generation Scanlations:

After getting dumped by his lover on Christmas Eve, Ei finds a young man with a cat covered under the snow outside of his apartment. That's how he met Junpei. The serious Ei makes some place in his heart for the young man and the kitten named Yakinori.

With each passing day Ei becomes happier and happier. Until one day Ei's ex returns. What will Ei do with this sudden development?

A love wound that is healing, drawn warmly to reflect a pure feeling. A collaboration jewel!

From Storm in Heaven:

"The solution to all love problems is sex." So prescribes Doctor Meishuu to his love sick patients. But when a patient confesses his love for the dear Doctor, can Doctor Meishuu still continue to stand by his philosophy?

A series of one-shots with the recurring character of Doctor Meishuu.

1-2)
Sonkai, Meishuu's friend, falls for a patient's grandson. Sonkai approaches the elegant young Suisei and befriends him... but suddenly, both he and his grandfather stop showing up at the clinic. Meishuu suggests they pay the old man and his grandson a visit and, determined to be with Suisei, Sonkai agrees. But who is this young woman with the old man, and why is there talk about a marriage?! Is Sonkai's chance slipping away?

3-5)
Meishuu will pretty much sleep with anything that walks... he's not picky about gender or position. Why? The root of all problems in love, of course - a heartbreaking first love. When a young martial arts student is introduced to Meishuu by Suisei, he is reminded of his first love. But the young Getsuei is not going to give his beautiful butterfly-like Meishuu up that easily...

Collection of stories:

1. If you Love an Arrogant Flower (1,2)
Kazuma, the unruly eldest son at a prestigious dry-goods store, dotes on Koutarou, the son of his father's mistress who was welcomed into the main house after the death of the latter's mother. But Koutarou rejected his confession and slipped through his hands. Then Kazuma is suddently attacked by the accomplished and serious second son, Ibuki! How will Kazuma react to his tenacity!?
2. Lonely Butler (1-3)
3. Loyal Dog Jeremy

SERIES 4: Diamond is Unbreakable
Diamond is Unbreakable follows Josuke Higashikata and his good friend Koichi Hirose as they protect their town from the influx of Stand users. Jotaro Kujo arrives to warn Josuke about the Bow and Arrow a mysterious man is using to bring out a person's Stand abilities, but it is up to Josuke, Koichi and their allies to defeat those who would use their Stand abilities for evil - most notably Yoshikage Kira.

Nanoka and Koshiro were separated at a young age when their parents divorced. Now, 10 years have passed, and Koshiro has already forgotten about his younger sister. Yet, Nanoka has decided to attend the nearby high school and come back to live with her father and brother. However, the two had met just before Nanoka came back to live together and without knowing each other's real identity, they went on a date, only to find out that they were actually siblings...

From Animexis:

On his way to school, Torii Akira helps a girl who was about to fall down. From that moment he keeps running into that girl, and she seems very happy to see Akira. Could this be the reason Akira can't help but smile all day?

From Aerandria Scans:

Kogure-sou is a crumbling old apartment building of just six rooms where four people live. On the first floor are the owner, a very old man who wants to have sex before he dies, and a girl in university who pines in a sad and complicated love. On the second floor are a salary man who finds meaning to his life in spying on the university girl below him, and Mayu whose boyfriend disappeared three years ago. Also involved are the florist from the nearby shop who worries over her husband's infidelity and Mine who is still troubled by a crime committed a long time ago. What all of them strive for is love, but they all find nothing but pain and bitter disappointments. Do they realize that what heals them is actually the run-down little apartment building and the real human warmth that they share with each other?

[From Storm in Heaven]:

Something happened to Kobato when he was young, something he can't explain. Since then he's been able to see things that normal people can't see. These are the touching tales of his and others' experiences with the unknown.

Contains three unrelated oneshots:
-Magic
-Ocean Floor Scenery
-Two Topics:Happiness Butterfly, Island Child

Vanilla by SHIMOTSUKI Kayoko

In an alternate history of the aftermath of World War II, Japan has been cleaved in half, with the south—Honshu and the other islands—allied with the United States and the northern island Hokkaido annexed by the enigmatic Union. It was on Hokkaido that a mysterious tower had been built, a strand of metal reaching up out of the atmosphere, visible from the northern tip of Honshu. In 1996, three teenagers, Hiroki, Takuya and Sayuri, make a pact—they will build an experimental aircraft, almost invisible to surveillance, cross over to Hokkaido and unlock the secrets of the tower. Their dream was never realized, because Sayuri was sent to Tokyo for treatment after she fell into a coma. It is now three years later. The rosy illusions of youth have fallen away, but not the unbreakable strength of the trio’s promise. The truth of the tower will be uncovered, and with it, the link between it and Sayuri’s mysterious, carefully tended condition.

This is a manga version of the film "The Place Promised in Our Early Days"

*Contains a short story called Pollyanna no Kishi (Pollyanna's Knight).

A collection of short stories published in the 40 year anniversary edition of Kodansha's Afternoon magazine, Go-Chan Magazine.

Rui Hasegawa is an unusual boy whose thoughts and actions are believed to be unconsciously controlling the global population due to extraterrestrial influence from an alien known as "X". When he has thoughts of suicide, the suicide rate goes up. When he decides to start drinking more milk, milk consumption around the world doubles- even those who are allergic begin consuming it and have to be hospitalized. To combat this bizarre problem, a group of people have sent a boy named Iruma to spy on Rui and make sure his life is as "normal" as possible.

from Sound of Jewels:

One day, Yukino received a weird message
from her best friend Saho.
Then when she came to school she heard about
her death. Truth is, she killed herself because
she was persecuted by her schoolmates...
So why is her last message "run"...?

(2) I’d Rather be Killed Under the Cherry Tree
Sasagawa is not the type who can easily make friends, yet Saho opens to her and they slowly end up to be the best of friends. When Yukino enters their group the balance is somehow broken. A short oneshot about friendship, love and betrayal. This is Sasagawa’s version of the story: Dead Friend’s Love Letter.
From Evil Flowers

By Shoujo Crusade: Sugimura Nozomi made a pact with her childhood friend Hyoudo Rei who both have a passion for ice-skating that when they grow up, they will both pair up to get into the Olympics. But then Rei moves away. Years later, Nozomi transfers to a school famous for its students' emphasis on ice skating. There she unexpectantly meets up with Rei only to find him indifferent to ice skating. But Nozomi will not give up on her dream even if Rei has and she's determined to make it to the school ice-skating club and bring Rei with her as her partner. Read this manga from right to left