One day, Taro Yamada, who runs a detective business, slips on a banana peel and reincarnates into Tsukushi Shikizaki, the younger brother of three beautiful big breasted sisters who will all die on the same day. As he spends time surrounded by the three beautiful sisters, he finds out that the boy he is reincarnated as will be killed by one of the three sisters ...!?

From MangaHelpers:

This 4-koma comedy manga follows the daily life of the intelligent, responsible 6th grade elementary school student Haruna Raika. She keeps busy as the elementary student council president and the classroom leader, and she even fills in for the teacher sometimes! [tethysdust]

-------------------
4-Koma comedy following the super genius grade school student Haruna Raika and her every day life. Where she's the class president, the room leader, the top student, and even fills in for the teacher when they've overslept!

Bi-Kwang is a handsome young warrior who becomes a drooling mess whenever he sees a pretty girl. Out on the road he meets an extraordinary swordfighter with no name who is searching for a legendary master warrior. Bi-Kwang promises to aid the swordfighter if he lets Bi-Kwang meet his beautiful sister. Of course, it turns out the swordfighter is the sister, Hwa-Rin Dahm, and she must switch identities to keep the plot moving along. Bi-Kwang is immediately smitten, and thus we have a triangle involving only two people.

This manhwa was made into a MMORPG.

The story starts with Sanda, a second year middle school student, getting attacked with a kitchen knife by his classmate Fuyumura.
While Sanda couldn't make sense of the situation at first, he gradually came to believe that Fuyumura's actions were just mean acts
stemming off from the latter having a peculiar puberty phase.

But that is all a misunderstanding. Fuyumura actually suspects that Sanda is the descendant of a certain lineage…

From Birdman, a superman from space, he received a mysterious mask and cape. Wearing these, even a slightly clumsy elementary student can transform into Perman, a hero of justice! Rescue the weak, thwart the evil. Together with his three friends, Perman does his best every day to protect peace on Earth!

Published in Indonesia by M&C Comics.

In the world of daily full-throttle dedication to his studies, there's Itsuki, a high school boy. The reason he's putting in so much effort into his studies is to reunite with his first love, a girl named Amane, and go on a date with her. While he's immersed in these study-centric days, by a twist of fate, he ends up living together with Amane and her sisters, Shion and Mone...!?

From PRISMS:
Wahhaman is a special robot soldier built ten thousand years ago by the Atlanteans. Found and dug up in present-day Toukyou, he doesn't remember anything, due to a nasty knock to the head he received at some point.

The world is not perfect. Learning to deal with its flaws is just a normal part of life. But there comes a point where these imperfections spawn a crushing realization... that something needs to change...

Due to the school bully's threat to get him game items, Ha Do-wan, the unlucky game shuttle, died after playing games all night long for a week. The moment he died, he got respawned to the classroom one week before he died... Everything is the same as that day. The only thing that has changed is the floating in front of him! What? Use the skills of the games I've played so far to beat the bully?!?!

Gratia, a girl considered useless and despised by her family, has a revealing dream where a mysterious man predicts a great future for her. She soon discovers that she is the lost daughter of the influential Luciffero family. In a surprising event, after being attacked, a golden light erupts from Gratia, forcing everyone around her to close their eyes.

When the light dissipates, young Gratia disappears and in her place an adult version of herself appears, with distinct features of Luciffero. With an imposing stature and undeniable beauty, she comes across Nea, her mother, and realizes that the transformation expected for the future happened that day.

This was the moment when ten-year-old Gratia and twenty-year-old Gratia switched bodies for the first time.

A mage named YuJin—gentle-hearted and righteous, but looks a little... scary. —makes a fateful choice: he will take Jeong Ain, the daughter of his late Master, under his wing and shape her into a Grand Mage.

In a world rescued by magic only to be plunged into chaos by its power, their destinies intertwine.

Together with the enigmatic yujin, step onto the perilous path toward becoming the next legendary Grand Mage!

“The Hero defeated the Demon King in the war of men against demons…” Those kinds of stories are a thing of the past. Nowadays, adventurers, demons, Heroes, Demon Kings, and so on are all occupations that no longer involve putting one’s life on the line. Peace has returned to the world, and dungeon exploration has now become a form of entertainment. Adventurers and monsters now all fight using clones they’ve created with magic in an extremely popular form of dungeon clearing where nobody dies. The footage of the dungeon getting cleared gets broadcasted all across the continent, and I’m a member of a Hero’s party that was ranked the 4th most popular in the world… but not anymore. Parties had a limitation of 5 members, and I was told that an unpopular job like Black Sorcerer would only get in the way of getting to 3rd place or beyond.

Now that I became unemployed, I was forced to find another party but I just couldn’t find one. One day, I encountered a beautiful blonde red-eyed woman who told me she had a job for me. After being so touched from having someone recognize my abilities far more than my past comrades, I ended up agreeing to take an interview without asking for the details. When I arrived at my destination, I was at the world’s hardest dungeon where no party has ever reached the final area, the Demon King Castle, where the Big Four and the Demon King were waiting for me. This is the story of a Black Sorcerer that was kicked out of a Hero’s party and joined the side of the Demon King Army to repel the Heroes. (Source: Novelupdates)

Or
Please read the title again.

Artist's Twitter (NSFW): https://twitter.com/kana_kkn
Orignal webnovel: https://ncode.syosetu.com/n4836fm/

Federal Informant ‘Baek Yisu’ and a criminal gang’s boss, ‘Baek Dogyeong’ are twin brothers.

With the same faces the two twin brothers have lived different lives until now. Yisu, who’s been betrayed by the gang, throws away his identity to become his brother. This federal agent is soon to become the gang’s boss…!

It's been ten years since the assassination of the Dragon King, the land's most powerful ruler. Off in the corner of the kingdom where tailed dragonfolk dwell, Jio, a human girl, yearns for adventure and an escape from rural life. However, when she meets the mysterious, amnesiac young man Neraid, Jio's life turns upside-down! With courage and curiosity knocking on the door, the two of them find the ultimate adventure waiting for them!! A traditional battle fantasy from a rookie artist begins!!

The virtual reality game “History of the Archana Continent” became part of reality, and “players” who were synchronized with humans appeared to protect the world. Lee Hoyeol, who was an ordinary salaryman, took over the body of the character he created in middle school, “Grandfell Claudi Arpeus Romeo.” Under normal circumstances, it would have been an absolute failure of a career, but Grandfell, whose occupation is a “demon hunter,” becomes extremely proud in front of demons! The only demon hunter in this world, Grandfell (= Lee Hoyeol) starts to make a move!

Lokan was the ‘King of Violence’ who reigned as the strongest in the virtual reality game, ‘The Lord’. Unfortunately, the assassination order issued by an enemy guild caused him to lose everything. To his surprise, the next time he woke up, he had returned back to three years ago!

“Fucking brats, just you wait. I’ll devour you all!”

A new story begins as Rokan, who travelled back in time, climbs his way back to the top!

Ririsa Suzunomiya, who is forced to live a cramped life at a girl's school where genuine ladies gather, is drawn to the sounds coming from the old school building...? The gorgeous and ladylike girls shout with beautiful sparks!

There are three female masters who are known to be the strongest in the world. The only thing they can’t get their hands on… their ideal man.

“If there are no ideal men, why not raise one yourself!?”

As they skim over the list of candidates, the ladies' eyes all fixate on one boy. A level 0 with no shred of talent…

After being betrayed and killed by the organization he worked at, the infamous assassin ‘Bi-Gwang’ reincarnates as ‘Kim Gyeongsoo’, a police officer. He vows to take revenge on ‘Hwaguksa’, the organization of killers that has betrayed him.

Living carefree at home is the greatest shortcut—my house is the world’s greatest Magic Power Spot. That being the case, both my house and I were summoned to another world by some guys who were aiming for it. However, I’ve been living in this place for many years and my body is, apparently, abnormally overflowing with magic. Due to some unforeseen circumstances by those guys who summoned me, they quickly ran away. Be that as it may, there are still some ill-mannered people who covet the magic leaking out of my house. I won’t give up my house to those people! I’m going to wield my power as I please!