Onodera Ritsu has just transferred from his father's publishing company to Marukawa Shoten. Assigned to the shoujo manga division, he crosses path with the person he'd least expected to meet. Takano Masamune is the editor-in-chief of the division Ritsu's been assigned to, and the two seem get off on the wrong foot right from the very start when Takano unexpectedly kisses him. However, there is more to than what meets the eye: Takano is actually Saga, Ritsu's senpai and high school love, whom Ritsu had thought to have played him for a fool by taking his affections for granted when he confessed and summarily dumped him.

Popular for Junjou Romantica, Shungiku's earlier works were more samurai romance/yaoi of this sort. Here we have a basic spoiled brat and his bodyguard developing feelings for one another.
by Yasha

The young pirate head Sakaki met the beautiful samurai Murou... Why did Murou have the other half of the treasure island map left by Sakaki's grandfather? Why did Murou keep to himself? Could Sakaki open Murou's closed heart? And how should he handle his best friend who loved him, Juurou?

From Sakura-Crisis:

One day, as Suzuri was walking past a river, she suddenly saw a HUGE peach slowly flowing! Due to the fact she has not eaten since the start of her journey, she decided to just conclude the huge peach was a god sent and did the most logical thing anyone would have done - eat it. However, just as she had her first bite, a young male jumps out of the peach! And before Suzuri knows it, she’s the 18th master to Momo who could do anything that Suzuri commands! What kind of danger would they encounter on their journey as they face a god that goes by the name Kyuui? And what dark secret does Momo have?!

Note: A redrawn remake started in 2015.

Isaka is secretly in love with his caretaker and former childhood friend Asahina. However, Asahina is obsessed with Isaka's father... or so it seems.

From Storm in Heaven:
After a scandal got him kicked out of his position at court, Takaaki's been idling the days away at his manor, impulsive and bored. Then one day his friend Naruhito stops by and tells him an insane story about the most beautiful woman alive -- and drags him off in his attempt to win her heart. Tagging along, Takaaki soon realizes that the "Princess" isn't exactly who she (he!?) seems to be. Who exactly is Princess Kaguya, and what is the dark secret behind her (his!?) past?

1-4) Tsuki wa Yamiyo ni Kakuru ga Gotoku
The rumor goes that sometimes, late at night, a white monster appears, and if you should look upon it you'll be devoured. One night, Tetsu happens to glimpse the man behind the monster, and decides that the man would be the one to teach him the sword and allow him to take his revenge. However, the swordmaster Shino is hardly interested in taking on any students. What will Tetsu have to do to get his revenge, and what happened to Shino in the past to turn him into who he is...?

5) Castilla
A dutch foreigner falls for a young samurai.

Junjou Romantica: Takahashi Misaki is suddenly having some unexpected and odd problems. What started as a need for some college entrance exam tutoring has somehow led him to being romanced by a suave older man who also happens to be his big brother’s best friend. Confused by all of his brand new emotions, Misaki struggles to deal with his suddenly very odd life. And if that wasn’t enough, his suitor, Usami Akihiko, has plenty of issues of his own. A man-child who decorates his room in giant teddy bears and toys, Usami is a famous novelist who also writes steamy boys’ love novels on the side. When Misaki cracks open one of these books and reads sentences like “Usami licks every inch of Misaki’s hot body”…well, let’s just say that all hell breaks loose. Plus it doesn't help with Usami claiming he's in love with him.

Junjou Egoist: Kamijou Hiroki is a broken man, consumed by unrequited love for his childhood friend, Usami Akihiko (the writer from Junjou Romantica). Along comes Kusama Nowaki, whose name "Nowaki" means "typhoon", an orphan working his way through life since middle school. Like the typhoon he is named for, he whirls into Hiroki's life and heart, blowing all resistance away before him.

Junjou Terrorist: As fate would have it, Miyagi Yoh (whom Hiroki is working with as assistant professor) and Takatsuki Shinobu, a high school student, cross paths. Bits of pieces start to link together from the first two stories. That aside, Miyagi, who has a sad hidden past in himself involving a relationship with his teacher, is faced with Shinobu, who just says whatever is on his mind. The wheel of destiny is beginning to turn once again...