Paraphrased from Impossibility:

Kiriko has always been overshadowed by her older sister Eiko. Eiko is cute, smart, and extremely popular, unlike Kiriko. This manga is about Kiriko leaving her sister's shadow.

Eriko Ichimura spends her high school days in complete obscurity. Her sole hobby is staring at handsome, smooth-spoken Akira "Omi-kun" Ohmi, and tweeting her daily fantasies under the screenname "Lovesick Ellie." One fateful day, she accidentally bears witness to Omi-kun's true self — and if that weren't enough, he sees her mortifying Twitter, too! Follow along with a plain, perverted girl, a two-faced boy, and their curious romance! [Kodansha]

In this colourful world, I lost all of my colours.
Then the boy shining in gold arrives to change it?

Ichika started high school with a lot of expectations, but hasn't been able to make any friends because she's too shy to talk to others. One day in the school backyard, Yuuya - a known ex-delinquent, feared by all his classmates - approaches her, and for some reason invites her to go to a karaoke place with him...
A beautiful and shy girl and an ex-delinquent, two introverted and lonely souls, make plans after school to achieve their dreams: be able to make friends!

Sixteen-year-old Yanagisawa Yae is our very optimistic heroine. Even when she was given only two options to pick from—either to move overseas with her parents due to their jobs or to move to the countryside to stay closer to her grandparents, she chose the latter. As she looked up the apartment she would be moving into, she ended up in a shrine. Since she is in the shrine anyways, she offers her prayer and tries out the fortune-notes. Incredibly, she picks up a "very good-luck" fortune-note yet it has only bad lucks written on it. The next day, despite of all her optimism, Yae finds herself struggling as misfortunes befall her one after another…

"I've been searching for two people my entire life."

A magician who spent her whole life in the Tower of Magic while holding her birth a secret, the ever-so-ignorant Sica Wolf.

"If you help me with my work, then I'll help you too."

Carthus Lian, the man who resembles her first love, suddenly appears in front of her.

And thus, their feelings for each other grow deeper as they went on an expedition to track down the demons who are a threat to the Empire.

Her first love or Carthus Lian.
What will be her choice?

From Simple Scans:
In the Spring she was 16, Takamiya Naho receives a strange, but detailed letter from herself, ten years in the future. At first she thinks the letter is a prank, but then the things written in the letter actually happen, including the new transfer student that sits next to her in class, Naruse Kakeru. The letter reads just like her diary entries, down to the same characters. It is not till two weeks later, when Kakeru shows back up at school, that Naho finishes the letter. In the letter, her 27-year-old self tells her 16-year-old self that her biggest regret is that Kakeru is no longer with them in the future, and asks her to watch him closely.

Note: Was nominated for the 20th Tezuka Osamu Cultural Prize in 2016.

From LemonadeScans: Kisaragi Maaya, 16 years old. The first love confession of her life was a complete rejection. She vowed to "never confess to someone again" until one day, the popular Chigira-kun who was on library duty with her, in order to heal his wound of unrequited love, proposed to her that they "heal each others broken hearts"! Everyday, being healed by Chigira-kun, Maaya starts thinging that she want to be closer... But, this is just comforting each other's broken heart. Even though she definitely can't fall in love with Chigira-kun-!!?

Mi Ryu's gorgeous, yet child-like mother is getting remarried. Now Mi Ryu has to meet her new family. Including a surprising, new stepsister, an "adorable" little brother, and another stepbrother that she has a crush on. And just when she thinks life couldn't get any worse....really?!

A count’s daughter who scored hopelessly on the school's exam, Rururia Talbot!

I was talking to my best friend Sarah while eating my favorite tart, before I ran into a fight between the Crown Prince Christoph and Duke’s daughter, Irene.

The fantasy rom-com of a count's daughter who wants to return home peacefully begins!

I'm a character in an otome game?!

I'm Vincent, the butler of the Count's daughter. One day, I suddenly remembered that this world is one of an otome game that I played in my previous life. Furthermore, I remembered that the lady I adore will die a violent death as the villainess! Huh? Don't mess with me! I'll destroy my lady's destruction flag!! As her loving butler (and a capture target), I'll do everything I can to help my lady avoid her bad end.

This is an intense isekai reincarnation comedy!

Chiharu and Maki have worked at the same company together for three years. They were both unceremoniously dumped this spring. As they got drunk together one night, they were both summoned to another world. They were given the very simple job of cleansing miasma.
Well, they had no choice now. They will drink and eat, and if possible, search for a boyfriend who wouldn’t cheat on them.
This is the beginning of their aimless journey through another world.

Makoto is suddenly confessed to by her narcissistic childhood friend Kikuchi Reita. Not even just any confession, he stands in the street and publicly says “If you want a boyfriend that badly, I don't mind going out with you”. Which was obviously a no, since Makoto has never considered Reita to be a man, especially a man of interest. What will become of her daily life now that Reita insists on her going out with him?

You may know the story of Princess of Nakrang, but behind the scenes of the ancient Nakrang Kingdom’s royal palace, unfolds the story of a different princess.The youngest princess of the Nakrang Kingdom, Seol is determined to pursue a different life from her sister Ran, who by unlucky fate, was persecuted by her father and brothers.The slave boy she rescued Miru, the odd-eyed Jamalta, and the one we know very well… The three men are in her fate.

In her first life, she was a Japanese college student who was raised in a family that favored physical prowess. In her second life, she was reincarnated into another world (not an otome game) as an orphan from the slums. She became hailed as the country's prophet, teaching several students who grew up to be some of the country's top elites. In her third and current life, she was reincarnated as a daughter of a noble family.

Born with the beauty and wealth she hoped for, she had thought that this time she would be able to live freely collecting cute things and indulging in fashion, things she was unable to do in her first life as she feared that they did not fit her. However, she discovered that not only had she been reborn into the same country where only 10 years had passed, but her father was her apprentice and her mother was the one who ran her over and killed her in her second life (lol). Before her death, she had seen four futures in which she would get rejected by different guys and another one where she would be killed. Remembering this, she made a resolution to experience a wonderful romance and hide her past as a prophet.

A certain human country has became prospered in exchange for sacrificing a maiden to a dragon.
But with their progressing civilization, humanity then found the power to defend their country without having to rely to the Dragon anymore.
Feeling that Dragon has became a relic of the past, they picked a priestess to kill the dragon.
However, the Dragon fell in love with the priestess at the first sight instead!
A new and upcoming "killing" romantic comedy!

Suzuna Inaba who graduated from the university and is going to live together with Seto. Their new life to make up from the one in two people start a new life of two tipsy that became a little adult ♪ a lot of delicious things!

A symptom which causes one to physically regress till the point of disappearance. A pharmaceutical company which claims to be researching a cure and the cause for this syndrome. What are their motives? And what does a dragon slayer and even a handful of demons have in relation to all this?

After successfully getting hired as a fashion designer, Mai rewarded herself with a trip to Kyoto and was just enjoying herself when she got struck by lightning at Honno-ji. She then loses consciousness awaking only to find Honno-ji ablaze. In the spur of the moment, she saves a person from being attacked, but it turns out he's Oda Nobunaga?! The popular romance game is finally being published as a comic!

From Sherbet Lemon:

Kaphisilia Ailide is the daughter of a noble duke. Ever since the disappearance of her elder brother, her parents have put all their pressure on her. Everyday she has to have sword fighting and etiquette class. Days before her father's birthday, she went to a forest of her family's confer territory to get him a present. All of the sudden a death wolf leaped out and tried to kill her. And then this strange guy...