Kang Ha Ji was a lovable, friendly girl who fell victim of bullying by the school's most popular girl because of her childhood friend Hong Min-Joo. Then one rainy day after an attempt to save a black cat from jumping into the road. She fell through a dimension crack and was transported to Cat's Kingdom.
"Did I found myself in a situation that's waaaay over my head because I met the Prince of this Kingdom?"

Fantasy Romance manhwa of an adorable cat's Bride.

From CoyoMoose & Turtle Paradise:

Third-year high school student Tachibana Kyou's world is shaken when a green-horn nurse suddenly arrives at his exclusively male school - the doe-eyed, baby-faced, and irresistably adorable Hirota Natsu. Completely taken with the new faculty member, Kyou abandons his playboy lifestyle for her, having found true love for the first time... But what will fate have in store for these two, engaged in the taboo relationship between teacher and pupil...!?

This is an adaptation of the Mirage of Blaze novel, and so far seems to follow the original source material closely.

The complex plot incorporates a large number of elements - including romantic melodrama, historical politics and supernatural fantasy. Japanese history predominates the heavily structured story-line, which mainly involves the continued aggression between power-wielding guardians ('possessors'), and the denizens of a 'feudal underworld'- a group of restless souls belonging to long-dead samurai from the Sengoku era who are attempting to re-ignite those age-old wars in present-day Japan.

Once upon a time there was a wonderful prince… A super rich and handsome prince with a genius IQ of 500, extraordinary physical prowess… An outrageously overpowered super star…!! What will happen when this ridiculously overpowered ultra-high spec boy and a certain ultra-level-headed ordinary girl meet…?!

17-year-old highschool student Rise is going out with her childhood friend Hiroomi, a young lawyer. Because of the age gap, Hiroomi imposes the condition that they do not have sexual contact until her graduation, however, Rise doesn't want to wait until then...

During the high school entrance ceremony, Koga Eito from the special class helps Kasuga Niina from her poor health. His gentle manner captivates Niina, making her confess her feeling towards him. Thus, the trials in love of this couple begin.
As time passes, Niina finds it difficult to continue loving him since there are instances when he seems to be playing with her feelings. For her, going out with Koga may bring a grim future to her.

The spam-mail boom of the near future: The great advances of technology, a new generation of improved systems, and ideal computer programs have caused a backlash. The IT world has advanced significantly to the point where humanoid "Spam" mails are causing trouble for their humans. In the near future, hundreds of thousands of spammers have caused incalculable destruction to the mainframe of the lives of everyday citizens. Enter "SM" Hunters to save the humans from our own creations. Can "Spam" ever be good?

From Udon Entertainment:

The Grim Peddler waltzes through fairy tales, giving the stories' inhabitants their hearts' desires. But benefactors beware, for his gifts don't always turn out quite as expected! Classic fables like Sleeping Beauty, Hansel and Gretel, The Frog Prince and more are turned on their side through the unexpected reversals and terrifying twists of this all-new series.

From StarryHeaven:

I’m Anna. I’m 14 years old and I’ve just entered the ninth grade. Sou and Hinata, who live in the same apartment complex as me, are my childhood friends and we’re all the same age. I thought that from now on we’d become even closer friends, but then Sou suddenly did that to me…!!

Akari couldn't think less of her school's karate champ, Abe-kun, despite him being the national champion. He's giant, uncouth, and couldn't be more different than her sweet angel and childhood friend, Takuto. But when Abe-kun injures his arm protecting her, she takes it upon herself to get him healed—after all, the school's pride is at stake—but finds the tables suddenly turned when he confesses to her! Now she's the goal he's aiming for, and she'll soon find out how driven a national champion can be!

ChuYu woke up to find herself in the body of a murdered princess almost half a millennium ago. She soon finds out that whoever wanted her dead was in her mansion. Knowing the history, she also realizes that the owner of her body will soon perish in a historical rebellion. Now she must defend herself in the depth of a forbidden city while preventing what is to come in her historical timeline. A palace epic filled with tactical battles and a hint of affection. Full-colour Web Comic Official Website: http://manhua.weibo.com/c/61087 (Copied from myanimelist.net)

After spending most of her youth fielding the attention of countless wealthy suitors, Suhee Kim finally finds true love with a steady boyfriend named Jinsu Han. But then tragedy strikes, and Suhee is murdered in cold blood.

To Suhee's surprise, she is immediately reincarnated as a baby girl named Sanghee Kim, who just so happens to be a princess! Plus, she is fully conscious of her past life. There's just one problem: in this society, women are seen as totally inferior, even princesses. Appalled by the treatment of women, Sanghee is determined to change the kingdom's patriarchal ways. Will Sanghee be able to succeed, or will she be stuck living her second life being treated as a lowly woman?

From Paperdolls Project:

"I want to smell... I want to touch... I want to kiss..." Feelings that cannot be satisfied by just staring at the boy you fall in love with. Kiss... is the desire emitted by a girl in love. An omnibus of 4 oneshots by Fuji Momo.

Yulia is reincarnated in a world set before the start of an otome game. She started working as a maid in the castle, but she is serving the princess who appears as a villain in the game! "I won't let this cute princess become a villain!" Rumored as a tough, impregnable maid, she herself will make sure to show the princess happiness! She will use her knowledge of her previous life and the life of magic to change the future of the game is what she thought, but for some reason, a knight who showed interest in her appears! Not taking falling in love into consideration, follow this talented maid through her fantasy!

In the prolonged absence of the King and Queen of the Kingdom of Hearts, their daughter, Princess Eleonor, was compelled to hastily ascend the throne.

At that moment, memories of Eleonor’s previous life came flooding back to her, and it dawned on her that the world in which she currently resides is that of an otome game she once played…?

All the words that pass her lips turn into venomous barbs, leading her down the destruction route at full speed—!!

From Kogarashi Scans:

Surrounded by 4 good-looking childhood friends, Mizuho's everyday life is full of nothing but heart-racing moments ♡ On top of that... Lately, Kizuki, the youngest among the group, has been drawing in steadfast towards her!? A dazzling tale of youth begins!

The first lieutenant of the Space Alliance Defence Force, Suna Kim, travels dimensionally to a fantasy world called Rofan! An extreme survival story plays out after she dies and reincarnates as the daughter of Duke Langtry, who was cursed and killed. The frugal lady travels in search of her spaceship, which crash landed in the unfamiliar and barren fantasy world. A lively and brutal romance in court!

Ohno Fumi is a poor 2nd year high school student. Because of her father's debts, she's kicked out of her own home and has to rely on her own connections to survive. Thus begins her life as a live-in housekeeper for a reclusive writer.

Chise has always believed: "Mom's actions are for my sake, so they're correct"—even when feeling suffocated. One night, she sees the delinquent classmate Asahi ride his bike with his friends, and starts to become intrigued by him...?

From Chibi Manga:
Staying together with a sadist teacher!? The “oni” is terrible, you know!!

A poor high school girl, Moka has to work for her living everyday. The rescue came from her admired teacher, Onimiya-sensei, but… Sensei’s true self is a sadist!? what will her life be now~!?