Velvet Kiss

A Manga published in 2009 by Takeshobo and serialized in Vitaman Magazine, it follows the story of Nitta Shin. After acquiring a crushing debt, his loan agent tells him that he can escape repayment if he keeps a particular woman company. After meeting up with Kanoko he gradually learns that this arrangement might not be as easy as he once thought.

The story of a salaryman and his meeting of a lonely, rich girl, Velvet Kiss is a typical Seinen masterfully done by Harumi Chihiro. It has three volumes currently out and is still ongoing. Digital Manga has acquired the license to release the first two volumes in the U.S.

Tropes used in Velvet Kiss include:

Allergic to Love: Kano doesn't really understand romantic gestures, especially kissing. The one time Nitta tried to kiss her, she just kind of stared at him blankly until he stopped. Later he tries a slightly indirect approach, which ends up freaking her out a little.
Am I Just a Toy to You?: The central point of Nitta's dilemma. He has an 80 million yen debt hanging over his head, and to pay it off, he has to cater to the whims of one girl, who generally treats him like a sex toy.
A Party - Also Known as an Orgy: The get-togethers Kano and her friends have on a regular basis.
Bitch in Sheep's Clothing: Kanoko's stepmother. Also Rumi.
Character Development: Kano goes through a bit of this through the story, Nitta does too.
Coitus Ensues: The story does have small elements of this, but most of the time it only focuses on Kano and Nitta.
Coitus Uninterruptus: In one, chapter Yuki, Kano's friend is getting a call from her saying she won't make it. He was currently getting a blow job from one of the girls and tells the girl to keep going because she just lost a bit of the mood.
Defrosting Ice Queen: One of the main points of the story is how Nitta (reluctantly) is getting Kano to open up.
Dysfunction Junction: Kano has plenty of issues, Nitta to some degree as well.
Enemy Mine: Nitta newest plan depends on finding people within company, who if not loyal to Kano's father like Ishizuka, at least hate her stepmother, in his words "There's gotta be Anti-Yoriko clique"
Everybody Has Lots of Sex
Evil Stepmother: Later chapters confirm that Kanoko's stepmother is this.
Friends with Benefits: This is how Kano's friends and her get along really.
Girlish Pigtails: Kano's default hairstyle
The Hedonist: Kano's orgy friends, but especially Yuki. Nitta's brother is a milder and a more positive example. Kano is also this at the beginning of the series, but receives Character Development, turning her into a lesser example
Horrible Judge of Character: Nitta, with the girlfriend who used his signature to borrow 80 million yen, Kanoko's stepmother who he judges as to be a gentle and caring person without bothering to double check this before trusting her and finally Rumi with whom his "accidental" meetings were more than a little suspicious.
Information Broker: Nitta's brother plays this role, getting details of Nitta's debt as a special one.
If It's You It's Okay: Kano seems to do only certain things with Nitta, that she doesn't do with her friends.
Good People Have Good Sex: It seems Kano likes sex with Nitta more than she does in an orgy with her "friends".
It Got Worse: The story so far has given a harder life for both our main characters...As of chapter 27, Nitta has lost his job and is a drunken wreck, Kano is about to lose her father's company to her step-mother.
Likes Older Women: There was a scene in one the 20s chapter where Yuki, Kano's friend, with in a room with that step mother of Kano's about to get busy.
Not So Different: Early in the story Nitta calls Kano out on what she does with her friends has no meaning, Kano retorts this trope to Nitta about him spending time with her to pay his debt.
The Ojou: Deconstructed. Kano's rich, but it doesn't seem that her father cares for her, she absolutely hates her stepmother, her friends are just people she has orgies with, and the best person around her was basically strongarmed into becoming a sex toy, and all but loathes her.
Porn with Plot: In accordance with Everybody Has Lots of Sex.
Primal Scene: Kano walked into one in her early childhood, might explain why she's a bit screwed up in the head.
Rich Bitch: How Nitta sees Kano
Tsundere: Kano is the classical version of the trope, leading to a deconstruction. Her behavior leaves Nitta none the wiser about her true feelings, causing him to hate her and get as far away from her as possible the moment she gives him spare time.
The Vamp: Kanoko's stepmother.
Villain Ball: Getting Nitta fired just freed him up to work against her
Vitriolic Best Buds: Kano and Nitta have started to become this.
With Friends Like These...: Kano's friends are....not the type of friends you normally see.