While on a high school field trip, a school bus crashes into a shrine of a penis god. This serves as a catalyst for a group of four high school boys to switch penises with each other. At first a rather typical yaoi, the series quickly delves into comedy antics with talking penises, penis costumes, and puns.
(Source: M-U)

V.1-2:

1-4. Komori Tadamachi loves teaching at an elementary school, the only problem is fellow teacher Takigawa Kyou. Always being compared to the perfectly composed and devastatingly handsome Takigawa (even by the students!) is really destroying Komori self-esteem. Still, Komori finds himself being drawn in by Takigawa's effortless charm...

5. Sensei no Kokuhaku (Sensei's Confession)
Kunihara Sensei is a handsome college prep teacher who is used to fending off the advances of his female students. But adorable and shy Kakei appears to have a crush on sensei too, only he won't admit it. As Kunihara tries to find a way to deal with male student admiration, he finds himself more and more interested in Kakei.

V.3-4 - Saikyou Kyoushi
Fujita is raising his elementary school son all by
himself. His enemy is the stiff teacher, Ibuki who is
actually called a “dangerous type” and a feared retired Yankee! Ibuki’s forceful and savage face as well as his sometimes gentle face, the Fujita who is tossed around by the two faces is…!?

The clumsy adult’s real love is here. Yamato Nase’s best book in history has finally arrived!!

Touji's daily routine is cooking, doing laundry, and cleaning... Before he knew it, he has become like a househusband who takes care of his large Udagawa family. One day Touji's cousin Yuuto joins the family and Touji cannot take his eyes off the innocent Yuuto. He even has erotic thoughts about Yuuto. With his feelings spinning out of control, what will happen to this itokon?!

Mizuki has just lost his job. Without money or a place to live, Mizuki has no choice but to stay with his older brother in his company dorm room. Since non-employees are not allowed in the dorm, Mizuki must live there in secret, like a house cat. At first Mizuki is intimidated by his older brother's roommate, Toru, but seeing a softer side of Toru changes his opinion. Toru starts to treat Mizuki with kindness, but Mizuki wants to become more than just a pet companion.

For various reasons, Kota Kuramoto lives a plain life without TV, oblivious to fads and fashions as a completely out-of-touch high school student. One day, he begins pummeling a boy who suddenly appears in his yard, not realizing the boy is none other than world-famous, super-popular actor Togo Kihara! Togo takes to Kota despite their first meeting and tips him handsomely to work as his attendant. Kota can’t help but accept Toga’s proposition—but when he sees Togo display his star aura on the set, Kota sees a Togo completely different from his snobbish, pushy, normal self. What happens next? This comic puts a super star and a high school pauper side-by-side for a story of star-crossed love!
(Source: JManga)

Shinohara Satoru didn't expect the big change to Tokyo to be easy, however his cast of neighbors isn't helping that, especially from Izumi Yuushin...

The calm, composed and shrewd restaurant owner, Hatakeyama, is in love with Yamasaki, the cool, beautiful chef from a rival restaurant. In the past, Hatakeyama tried to embrace him and Yamasaki hates him for it. Despite this, Hatakeyama refuses to give up and aims to start again as friends. Although Hatakeyama often asks him out to eat, Yamasaki still doesn't show any interest in him... but what happens when a cool, good-looking fellow chef appears?

Hamura is a sheltered and very friendly high school student. He has always admired Miyake from afar who is very reserved and troubled. An incident in the locker room has finally opened up a chance for Hamura to be friends with Miyake. But does Miyake want a friend... or could they even be friends? Between Miyake's troubled past, Hamura's jealous close friend and preverted tutor, how will these two make any type of relationship...

Haruhiko has just been confided by his friend, Kyotarou, that he is seeing someone. That "significant other," turns out to be Nao, a young elementary school boy. Nao's mother died when he was younger and the only person taking care of him is his dad, Hirofumi. Scared that Hirofumi might find out about their relationship, Kyotarou asks Haruhiko to tag along on their outings to disguise the relationship from Hirofumi. Haruhiko reluctantly agrees but what he hadn't expected was to develop feelings for Nao's father.

Volume 1:
I want to be a successful man like Hongou-san as well!
Kazuha, a na?ve boy from the countryside dreamed about working under Hongou, who manages a restaurant in Tokyo. After cheerfully arriving in Tokyo, what awaits is a person who is totally different from the Hongou he admires. He never hides his temper and is a super selfish guy! While disregarding Kazuha’s uneasiness, Hongou made Kazuha live with him?!

Daiki comes home from a luxurious life in Tokyo to find that his childhood friend, Tetsu, has grown into a strong and surly young man. Daiki's struggle with belonging becomes even more complicated when Tetsu harbors strange feelings toward Daiki!

Noboru seems to have rotten luck at school when it comes to girls, because they all have eyes for only Yuuki – the resident Prince Charming. Tall, dark, rich and handsome Yuuki seems to be the exact opposite of the poor, short and not very manly, Noboru. Because Noboru is from a poor family, he had to work extra hard just to get into this prestigious Seihou Academy – which is mainly reserved for the rich and elites of the society. Before admittance, it was a dream of Noburo to hook up with one of the rich girls at Seihou Academy, but his plans seems to have gone awry, specially when all the girls seems to not pay him much attention and dotes on Yuuki the most. But for some reason, why does this drop-dead, gorgeous hunk, Yuuki, seem to want to get close to him???

From Forever More:
Summary vol.02: The truth is, I think that I might already be caught in his trap. As usual, Yuuki's attacks are fierce,...and he's sometimes kind, and it's just the matter of a countdown until we have our happy end...I think that, too. But. But, well. He really is a rich kid, and I'm just an ordinary guy. The worlds we live in are different. Incidents happen to make me realize that again. Yuuki... are you going to go so far as to take away my pride?!

Summary vol.03: Yuuki's a snob, but he's also earnest and passionate. He's been courting me, and I've slowly fallen for him. He's my boyfriend now. My brothers have gotten attached to him too, and he jokes that he wants to marry me and join my family. But Kazushi-sempai doesn't like the thought of Yuuki being happy. He told Yuuki's older brother, who's living in America, about our relationship. His brother came back to Japan and told the two of us to break things off. Now Yuuki's rebelled against him and ran away from home...?

* Contains a oneshot called Pleasure Point in vol. 1:
Kubota is the only child of a massage parlour and hopes to enter that profession later in life. Using that as an excuse, Kubota insists on practicing his perverted massage techniques on his classmate Haigara. But when the massages start to become effective, Haigara's not sure what to think. And what's this about the pressure point connected to the heart? (from p-s)

Chintsubu A)
Part 1 - Iwabuchi starts hanging out with girls from his cram school, and Kamiya-chinko freaks out. What is he up to?
Part 2 - Toride's soul moves up to Ayase's nipple and covers their issues about this new development.
Chintsubu B)
When Iwabuchi engages in more chinko cosplay, Kamiya is upset and they get into another fight. The cosplay chinkos are not to be missed in this!
Chintsubu C)
Part 1 - The chinkos have a big discussion over what to do when they want to get off and their "bodies" don't.
Part 2 - Gives us the backstory on Iwabuchi's first impressions of Kamiya, when they first met long before the accident.
Chintsubu D)
Kamiya injures his hand and can't engage in mutual jerking off with Iwabuchi, leading to a REALLY big fight.
Chintsubu E)
It's summer and the chinko alliance head to the pool for some swimming fun, but can chinkos even swim?
Chintsubu F)
When Toride-chinko disappears one night, Ayase panics. The next morning, Hiro reveals that he has performed a successful remote exorcism on Toride-chinko, but when Toride-kun shows up at school with no memory of Ayase or the chinbi (chinko secret), Ayase tries to be optimistic about making Toride-kun fall for him all over again. What happened to Toride-chinko? Is he gone for good? Will Toride remember the chinbi and his feelings for Ayase?
Chintsubu G)
In this installment of Chintsubu, Torite must come to terms with the fact that his chinko talks—and it's fixated on Ayase. Ayase struggles to resurrect Torite's memories the only way he knows how—by working some hand magic on Torite-chinko. Unfortunately, he fails his mission and freaks Torite out in the process. Will Torite-kun be able to accept his wacky anatomy as anything other than a strange hallucination? And will he find the courage to talk to Ayase again, or will his fear of his over-excited appendage keep him down? This couple's drama gives Kamiya plenty of food for thought regarding his own relationship with Iwabuchi.
(Source: Liquid Passion)

Three young men have been friends for the past 20 years. Kanato, an average guy who owns a family business, has had feelings for Sora, a cheerful young man with an unlucky past, for the past 10 years. Afraid that this can change their relationship, Kanato has been hesitant about confessing for a long time and ended up confiding first in Shin, a handsome business man. Although he finally musters up the courage to declare his feelings, before he gets the chance to confess to Sora himself, a different confession dissolves all his expectations and everything changes.

Youhei immediately fell in love with the actor on the late night advertisement, Satomi. After going through some random events, they became lovers. However, how will these two love birds face the upcoming events which involves costumes, a manager, a stalker and maybe an old crush!?

Fumiya sees spirits, while his childhood friend, who's the temple's son, doesn't. Ghosts and spirits work to drive these two together.

[Taken from FantasyShrine] :

Youhei immediately fell in love with the actor on the late night advertisement, Satomi. After going through some random events, they became lovers. However, how will these two love birds face the upcoming events which involves costumes, a manager, a stalker and maybe an old crush!? Another enjoyable series by Yamato Nase, full of romance and humour!!!

Takao-kun is deeply obsessed with his older brother - a clumsy but nice teacher.
His brother suddenly has some serious problems because of one student. Takao decides to become friends with this rich and annoying boy to help out his brother. Will he succeed? Who is the mysterious brother-stalker?!