Yagami-kun's Family Affairs follows Yūji Yagami, a high school student with a problem: his mother, Nomi, looks very young and Yūji has a crush on her. To complicate matters, his high school homeroom teacher is also infatuated with her due to how young she looks. Nomi is oblivious to all of this and is head over heels in love with her husband, Yōji, and frequently displays this affection very publicly, which causes more embarrassment for Yūji.

Yūji's high school friends constantly tease him about his "mother complex". When Valentine's Day comes around, though, Yūji receives a box of handmade chocolates. The name on card can be read multiple ways, the most common way being Masayuki Ikari (五十里 真幸 ,Ikari Masayuki?), a male name, so his friends tease him throughout the day until it's time to meet the person who sent the chocolates at the front gate after school.

The girl who sent the chocolates (the name is actually read "Mayuki") starts meeting him after school so they can walk home together, and they eventually become an item. The remainder of the story follows Yūji and Mayuki as their love grows and as Yūji works to resolve his "mother complex" issues.

A demon boy who lacks horns on his head wields the cursed blade "Onikirimaru", the one weapon that can slay a demon, in a never-ending battle with the demons that haunt Japan during the age of the samurai. Behind the stories of Oda Nobunaga, Toyotomi Hidetsugu, Ishida Mitsunari and the other famous generals of the Japanese civil wars lurk secrets and demons...

An astonishingly deep story about these demons and the sword Onikirimaru! And this also includes the secrets of Onikirimaru's birth, which readers have always wanted to know. The legend of Onikirimaru explains clearly how Onikiri was born, and the hidden secrets of his past. Behold the battle between the darkness of the age of the samurai and Onikirimaru!

(Source: Crunchyroll)

Soon after transferring to a new school, Mayu Kodabutsu receives a love letter from a cute girl named Yuuko Hai. Expecting the envy of his classmates, Mayu is surprised to receive condolences instead. You see, Yuuko Hai is no ordinary 5th grader... she's an exorcist. And Mayu is destined to experience her 100 terrifying ways.

(Source: MangaWorld)

Shingo Chiryuu isn't much different than any other guy except for one thing... He's afraid of girls. When he was younger, he was attacked by an overweight girl, which caused him to develop a fear of woman, seeing them all as "dinosaurs." But even with all his efforts to get away from the girls, they seem always be there, making trouble for him along the way. Now he finds himself surrounded by girls, including the one whose attack originally instilled the fear in him, as he attempts to cure himself of his gynophobia.

Summary by totochan:
What does a high school boy have to do in order to make the love of his life remember you in *this* lifetime? Cosplay? Host a "this is your previous life" audition? Show her all your good points? Just because she is a manga otaku in love with Blue-Sama. It's not like falling in love with manga characters is based on real life?

Suwa Daisuke is the ladies man of his small town high school, and he has his eye on almost every girl, except for one. Aikawa Hinako isn't his type, but when he overhears a deep dark secret of hers, he finds himself thinking of her more and more.

There was once an ogre (oni) mother who gave birth to a human looking child. Instead of an ogre's horn, this child was born with a sword in hand called the "Onigirimaru" or Ogre Slayer. He has no name and is only refered to by the name of his sword. Though he appears human, he is pure ogre. Believing that he will become human once all of his kind have vanished from the world of humans, he sets out on his destiny to slay all of his kind. Even now, in the mother world of Japan, he is still out there slaying ogres.
(Source: ANN)

From Wingtip Cafe:
When a vampire is in love with a human...

From RebelliousArt:
Asahi, desperate after the loss of her best friend and boyfriend, came to the abandoned elementary school above the hill. It has been said that it's a cursed place that it will be the last place you will tread in. Those who live will not be able to return. And there, Asahi meets...!?

Sengoku was a period when Japan was in war, a period when humans were still able to communicate with Gods. Young Sarutahiko has died because of the struggle, but he will be resurrected and turn into an immortal thanks to a God's power in exchange of consuming his sister's life day by day.

To save her, Sarutahiko will ask for help to the God of the Mountain, but instead, he meets a beautiful young girl... What is the true identity of this girl?! What kind of God is capable of granting wishes in exchange of souls, blood and death...?!

Shingo Chiryuu isn't much different than any other guy except for one thing... He's afraid of girls. Now he finds himself surrounded by girls, including the one whose attack originally instilled the fear in him, as he attempts to cure himself of his gynophobia.

A more serious manga from Kusunoki Kei (Girls Saurus, Dokkan Love, 100 Ways of an Exorcist).

Daria is a relatively normal girl, despite the fact that she always seems to be the recipient of miracles. But when a strange character appears suddenly, with the intention of keeping his promise to kill her, her average high school life becomes anything but...

From Tokyopop:
Masayoshi Kurozuka is an ordinary high school boy... until the day he discovers that he is the reincarnation of an evil woman named Oni-hime, who sold her soul to the devil during Japan's warring period.
Masayoshi must come to grips with his identity, all the while fighting off legions of ghosts -- the remnants of men killed by Oni-hime. In order to free himself from this curse, Masayoshi must discover the truth behind Oni-hime's deal with the devil and clear her name in the eyes of the restless spirits seeking revenge.