Hentai Manga like Natsume-san wa Hirakaretai

Torotoro Hitou de Koi, Hajimaru.

Also known as A Steamy Romance Blossoms at the Secret Springs.

Status: Finished
Genres: Romance

Iharu is a university student looking for ways to kill time over spring break. In passing, he meets an attractive young man named Shin who invites him on a trip to the hot springs. He accepts Shin's offer and finds himself at an elegant inn with outdoor baths and hidden springs--not to mention luxurious meals and amazing sake... Lost in his happiness, he decides to enter the hot springs with Shin. But when he looks at the young man undressing, he can't believe his eyes... "Even his dick is gorgeous! His butt is so shapely!" Even after Iharu turns in for the night, he can't stop thinking about Shin's amazing body... and growing increasingly horny.

Good Teacher

Also known as The Good Teacher.

Status: Finished
Genres: Romance

Ho-Jun’s recent breakup was pretty rough. His partner told him it wasn’t him, per se… Ho-Jun just wasn’t good in bed. But it turns out Drunk Ho-Jun is surprisingly resourceful; singlehandedly managing to find and set himself up with a sex tutor by the name of Mr. An. An Seung-Hyeon was only half serious when he posted the sex tutor ad, but he quickly finds himself in too deep to call the lessons off. And the more he sees Ho-Jun, the more he can’t help but notice how much attractive he is. Seung-Hyeon is making it up as he goes along, so what will the final exam look like?

Kimi no Ashimoto de Ai wo shiru

Also known as Learning to Love at Your Feet.

Status: Finished
Genres: Comedy , Drama , Romance

In this world, in addition to being male or female, people are divided into two "dynamics": those who yearn to control and those who yearn to be controlled. Kippei's a regular office worker who's always hated being the latter. But, suppressing his desire has stressed him out to the point of making him sick. Finally, he goes to the doctor, who tells him the last thing he wants to hear: he needs to find a partner and get some release! Kippei signs up for a matchmaking program, only to get paired with a guy who happens to be his hot coworker Sota Otomo.

Vivarium

Also known as Vivarium.

Status: Finished
Genres: Drama , Psychological , Romance

Yoo Heesung is…not a nice person, to say the least. Arrogant, selfish, and criminally lacking in loyalty. So when he decides to steal from his childhood friend, their years of history don’t really weigh upon his mind. Until he wakes up, head pounding, tied to the bed of a dingy room?! Choi Jaeyeon knows just how awful Heesung can be, and is determined to teach him a lesson he will never forget.

Note: Chapter count includes an epilogue and 6 side story chapters.