Ao Sato is accidentally swapped with himself in a parallel world with a male/female ratio of 1:39.

He finds a kind family and lovely women at the place where he was switched.

Seeing the outside of these women, he's relieved to see that the number of men and women has changed, but not much else.

However, their inner lives are filled with conflicts and troubles.

Shinichi Kudo is a high-school student who, by using observation and deduction, is good at solving mysteries. While investigating one, he is caught by the criminals that he was watching and forced to take an experimental drug. Leaving him for dead, the criminals disappear. Instead of killing him, however, the drug turns Shinichi into a little kid.
To preserve the illusion of his 'disappearance,' Shinichi adopts a new name based on his favorite author (Arthur Conan Doyle) and becomes Conan Edogawa. Ran, his (actually Shinichi's) childhood friend takes this little boy under her wing and brings him to her home.
Conan now lives at a detective agency run by Ran's father, but his mind is as keen as ever and he continues to solve mysteries... always allowing Ran's father to take all the credit.
As far as everyone's concerned, Conan is just a little kid anyway... even to Ran. This is *extremely* frustrating to Conan since nobody will listen to a 'little boy.' Despite this, Conan has a mission... to find the criminals who did this to him and get the antidote to that drug.

Note: Won the 46th Shogakukan Manga Award in the shōnen category in 2001.

For as long as he remembers, Komi has been shorter than his fellow classmates. He always felt inferior as a result, until he met Obinata - a girl who is head and shoulders above him.

Yes, Asumi Obinata is tall. She’s imposing. But she’s also Komi Amane’s girlfriend. And these two are the happiest kids in the world.

The super-popular oneshot has been expanded to a full series here!

Jung Yeonshin was born with a short fate: being unable to live past the age of twenty. Although everyone in his family looked down on him, his skills were remarkable enough for him to create his own martial arts. One day, Yeonshin realized that he doesn’t have much time left to live… This is where Jung Yeonshin, a terminally-ill genius, begins his desperate struggle to survive!

Today, as the invasion war by extraterrestrials comes to an end, the hero Shibusaki Takashi retires from the military and returns to Japan. After escaping from days spent on the brink of death, the normal high school life he had long dreamed of finally begins... filled with anticipation, Takashi looks forward to it. However, in reality, his daily life is turned upside down by a group of unique and beautiful girls, including his comrade from Northern Europe, Natalie, and he finds himself caught up in unexpected battles every day! Has his life stopped being normal because he himself has changed...?

Kanan is a demon hiding in a high school in the human world to feed on the souls of humans. She sets her sights on a single high school boy, but somehow ends up in a lovers contract with him!? Kanan, who has never been in love, is now filled with new feelings!

The romantic comedy of a pure-hearted demon's first love, begins!

(Source: Shounen Magazine, translated)

Seto is a serious kid who leads a quiet High-school life, until he starts to get teased by resident Gal Anjo.

My wife is suspicious!! Why did she marry a guy like me…? Ordinary average guy Tsuchioka Naotsugu ended up with Yoshino, who's perfect in all angles of beauty, know-how, and sociability. It's not "marriage blue" it's everyday life questioning over things, so it's "marriage gray" newlywed life, go!

The first unique romantic comedy manga in the history of CoroCoro! The slime he created transformed into a girl!? Kotarou, a young boy, is constantly pushed around by Puniru's freewheeling behavior. It's a fun and exciting daily life!

The count's daughter, Psyche, is loved by all. Psyche, who took everything from me. Psyche, who always gets what she wants. I wanted to be her, even if just for a day.

Now officially serialized!

A 34-years-old NEET otaku is chased out from his house by his family. Unattractive and penniless, he finds that he has reached a dead end in life and realizes that his life actually could have been much better if he had made better choices in the past.

Just when he was at the point of regret, he saw a truck moving at a fast speed straight towards three high schoolers in its path. Mustering all the strength he had, he tried to save them and ended up getting run over by the truck, quickly ending his life.

The next time he opened his eyes, he was already reincarnated into a world of sword and magic as Rudeus Greyrat. Born to a new world, a new life, Rudeus decided that, "This time, I'll really live my life to the fullest with no regret!" Thus, starts the journey of a man yearning to restart his life.

The daughter of a duke, the stuttering Maximilian, married a knight of lowly status at her father’s coercion.

After their first night, her husband departed for an expedition without another word.

He comes back three years later, this time as a famous knight in the whole continent.

How would Maximilian face him on his return?

"The more I think of you, the more lonely and lonely I become. I don't know why I can't quit even though it's so painful."

The series follows Meisuke Nueno, better known as Nube, an exorcist who also happens to be the teacher for a 5th grade class at Domori Elementary. While he uses many various exorcism techniques, his main weapon is the Demon Hand (Oni no Te) which is the power of a chaotic oni sealed right where his left hand should be. The series follows Nube and Domori class 5-3 though the many weird, chaotic, and downright silly and insane encounters they face with the many forms and elements of the supernatural.

Amelia, who dreamed of becoming an alchemist and worked hard, became the youngest alchemist in history to be appointed court alchemist.
However, she was harassed daily in her work at court.
In addition, her fiancé broke off the engagement and she has been exiled from court.
Amelia, who has lost everything, finds happiness in a new place with her childhood friend Thomas, with whom she has reunited...?

Yamato loves his little sister. His sister is the cutest and sweetest girl in the world, and he won't settle for second best. Unfortunately, everyday life and the rest of the world intrude on his idyllic plans, and he finds it's not as simple as he imagines it should be. Follow along with tough Yamato and cute Masaki as they deal with the problems of an otherwise normal family life.

"They" are real... One month has passed since the Great Shizuoka Earthquake. Marine research organization JANSTEC has been conducting observations of submarine faults in order to uncover the cause of the massive quake. Yadorigi, a blind young man working as a sonarman, assists in navigating the manned deep-sea submersible when they make a discovery...

In the year 1947, the people of Shinjuku are down on their luck. With little money to buy food or necessities, some resort to gambling in order to survive. Traveling Tetsuya chooses to spend his time at Mahjong parlors where he is wiping the floor clean with his adversaries. However, Tetsuya meets the intensely-skilled Boushu-san, this is when he realizes that his skills are still lacking.

Note: Won the 2000 Kodansha Manga Award for shounen.

I, Yvonne, reincarnated into an otome game as the rich villainess. According to the game's plot, a character loathed by everyone such as myself has the main role of bullying the heroine, pushing her towards the various love interests' romantic routes. But it seems like there's something wrong with Elsa, the heroine! She's getting too close to me!

Note: The translation of the original web novel can be found here: https://dynasty-scans.com/series/please_bully_me_miss_villainess_novel_ver

High school student, Kawasemi, who has transferred to the countryside, spends her days alone due to her shyness. One day, she is approached by her classmate Misago, a so-called 'countryside Yankee', and was taken to the mountains. Kawasemi was afraid of what she would do, but then MIsago starts fishing!? A Cooking lover JK Meets Fishing lover JK's outdoor life manga!

Ragna, the heir to a frontier noble family, is a reincarnated former Japanese citizen who realizes that the world he now lives in is the setting of an otome game. Dreaming of a carefree life as an adventurer, his plans are derailed when a war takes his family, forcing him to take on the responsibilities of managing his family’s lands.

Struggling with the unfamiliar duties of a lord, his already chaotic life takes another turn when an unexpected engagement to a noblewoman from a higher-ranking family is arranged.

To his surprise, the bride-to-be is Alicia, the "villainess" of the otome game’s story — a character destined for heartbreak, a demonic pact, and ultimate destruction. Now sharing his life with someone fated for tragedy, Ragna is swept up in the wheels of fate.

Can he rewrite the predetermined outcomes of this world and secure a peaceful life for himself and Alicia?