The MC transmigrated into a novel and became an extra from the novel. The novel is a murder thriller and the main character is a serial killer. He kills criminals with black magic making him a dark hero (think of him as Dexter or batman with dark magic). MC doesn’t have any death flags since she’s a background extra but she was a homeless girl of all things in such a dangerous novel. Somehow our MC saves the male lead and to thank her, he adopts her.

“Become my daughter.”

The richest, most powerful, and handsome duke commands her to be his child. The MC is freaked out since she knows he’s a cold blooded killer. Can she survive such a maniac?
Yet he dotes on her and constantly says my daughter is the cutest! He wants to get master artists to draw her and gather poets to describe her adorableness. The duke has a son. The apple doesn’t fall far from the tree; he also dotes on her. In this way a beggar became a little princess. She also got used to people getting killed.

However there was still one problem.

Our MC has turned sixteen and is wondering as a lady, will she have an arranged marriage? The whole house atmosphere quickly turns awkward. She realizes, perhaps they want her to stay here forever? Can she escape such a strange house? Everyone is so attached to her!

The protagonist of the series is the lecherous Satonaka Ikkou, who transforms into a super-monk (being able to perform mass exorcisms) by his lust for the girls he lives with. He lives in the Saienji Buddhist Temple as a Buddhist priest-in-training together with six other nuns: Amanogawa Haruka, Ikuina Sumi, sisters Sugai Sakura & Hinata, Nambu Chitose and Atouda Yuuko, each of whom represent one of the bosatsu of the six lower realms of the traditional Buddhist cosmology. Chitose is the other main character and has a strange relationship with Ikkou; he seems to be in all the wrong places at all the wrong times, but they really care for each other in all actuality. A side effect of Ikkou using his ultimate power is that immediately afterwards, he turns into an even bigger pervert than he normally is. The series is about Ikkou's self-destructive power and his attempts to control it.

Mochizuki's high school life suddenly took an interesting turn when he reunited with his childhood friend, Tsukimi Kawaru, whom he had a crush on since they were in elementary. Through a coincidence accident, he found out that Kawaru is actually a wolf girl, who couldn't control herself around him. Because Kawaru broke her promise of keeping herself in check, her sister, Utsuru, decided to pull her back home, but Mochizuki didn't like that idea and he came up with a solution to allow Kawaru to continue attending high school while keeping her identity a secret...

Thor Regus, a boy who lived in the empire, was banished to the territory of the Demon Lord by the hands of his father, the Duke. The reason was that he could only use [Alchemy] and didn’t have any combat skills. The empire was a military country, and those without combat skills were discriminated against. That is why the Empire decided to make him a hostage and sacrifice to the Demon Territory.

A graduate from the school of hard knocks, hit man Ogami faces his greatest challenge yet…middle school!

In order to be bought by a rich family, Narumi Inoue, hiding the truth that he is a man, goes to a girls' school. As a trainee, Narumi was sent to serve a girl from a rich family who hates maids (only weekends). Keeping the 'heart of treating/serving people,' Japanese maid, Maid in Japan, Narumi's battle will start? If it is found out that Narumi is a man, he will be castrated.

The previous lords have committed as many atrocities as possible to fill their bellies. I, the only daughter of that house, had discovered that my servant and lover was a spy. And as the people wanted, my life ended with my execution.

However, with the memory of getting beheaded intact, I began a new life. I was planning to shoulder the sins of my past life and become a nun, but by some trick of fate, I came to work as a maid for the current lord. Under my former lover, whose name, age and even hair color were all lies.

A gyaru named Serina is reincarnated into the world of an otome game as a background character who is sold off by her family and now works as the exclusive maid of the game's villainess Almelia. Yuri romcom hijinks ensue.

The school nurse feared by everyone, with her white underwear peeking out of her black tights.
And then she caught me peeping at it..... Thus began the s.e.c.r.e.t afterschool counseling

Mishina Tamaki is an orphan girl who left her village to study in the city. On a hot afternoon, while she was looking for a place to stay, she fainted. Upon waking up, she realized she was picked up by a playful rock musician. The story of their cohabitation that could (probably) turn into love, starts!

Spin-Off of CRIMSONS - Akai Koukaishatachi

The series, set in Saitama, follows the story of Ren Mihashi. Mihashi was the previous ace pitcher in his middle school's baseball team, but it seems that he only got the position because his grandfather was the owner of the school. His teammates (especially the team's catcher, Hatake) hated him, and they always lost their games. Mihashi is thoroughly convinced that he is a lousy baseball pitcher, and feels guilty because he believes that he is responsible for all the losses. Mihashi graduates through middle school with extremely low self-esteem. But in truth Mihashi is really a hardworking and skillful pitcher, and the main reason why his team always lost all the games is because of bad cooperation, because his teammates never talked about the game with him, and they did not try to come up with a plan or strategy to fight against their rivals. Mihashi then transfers to Nishiura High School with plans of quitting baseball because he thinks he is not good enough to succeed at it, though he still loves the game deeply. However, he is dragged into Nishiura's baseball team by their coach, Momoe, while watching the team training outside the field. Assisted by his new teammates (and especially the catcher, Takaya Abe), he grows in stature, confidence and skill, helping his team excel with his own abilities.

Won the Kodansha Manga Award for general manga in 2007. Won the Creative Award at 10th Tezuka Osamu Cultural Prize in 2006.

From Panda Scans:

Sanjou Arashi is a serious and reliable second-year high-school student working part-time at a detective agency. Her boss is a gambling, irresponsible, tobacco smelling oji-san. The pair are complete opposites, but this is the story of a scruffy oji-san X high-school girl romantic comedy!

Tenma Gabriel White graduates Angel College as top of the class and is sent down to earth, along with her classmate Angels to study Humans as a High School student to learn how to better lead them down a righteous path.
At least that is how it should have gone down. Instead Gabriel got addicted to video games and junk food. She even tries to skip school. A failure of an Angel.
Luckliy her Angel-like Demon friend Vignette April Tsukinose helps keeping her on track. Especially by remarking that No-Good Angels get deported back to Heaven. A fate Gabriel wants to avoid because she thinks that her lazy self is her true self, and because Heaven is now too boring for her.
At school Vignette's Demon buddy Satanichia McDowell Kurumizawa causes mischief from time to time. She is egged on by an Angel named Raphiel Ainsworth Shiraha (2nd-best in class after Gabriel) who has slight Sadistic tendencies towards Satanichia.
From time to time Gabriel's shy Angel-underclassmen Tapris Sugarbell Chisaki pays her school a visit.

A lazy Angel, an Angel-like Demon and her pompous Demon-buddy Satanichia and Satanichia sadistic Angel "follower" in one High school.

Hijinks ensue.

The comedy manga follows a male part-time late-night convenience store worker named Matsukoma, and the new part-time worker he trains named Tomoharu Nii, nicknamed Nietzsche-sensei. Tomoharu is a university student in the school's Buddhism department. When an angry customer screams at Tomoharu, "Customers are gods!," he replies, "God is dead." The manga follows the part-time worker life of Matsukoma and Tomoharu, the latter of whom continuously baffles his customers and co-workers at the convenience store with his odd ways.[ANN]

Yeon-woo had a twin brother who disappeared five years ago. One day, a pocket watch left by his brother returned to his possession. Inside, he found a hidden diary in which was recorded “By the time you hear this, I guess I will be already dead….”

Alexander, whose hometown was destroyed by the demon race, fought with the Demon King and was killed. But instead of the afterlife welcoming him, when he opened his eyes, he was reborn as the Demon King's son, Jilbagias!? While hiding his true identity, he stains his hands with atrocities as he conducts himself as the ideal demon prince, increasing his power to ultimately overthrow the Demon Kingdom...

A new story begins with Watanuki and Yuuko, while guests wishes are granted. Description by LuffyNoTomo

Fushimi Hina is the most universally recognized S-class beauty in the school. She is a childhood friend of Ryo, but they hardly spoke to each other from junior high school, but one thing leads them to talk to each other again.

Saku Kanakura was a boy born into a poor household. He studied hard and managed to pass the exam to an excellent high school but, it soon turned out that his parents were in debt! When it was time to pay the debt off, a mysterious gal appeared and offered to pay off their debt. A big burden was almost off Kanakura's head, but the gal made a condition in return which stated that—