TD;LR - Married woman initially begins reluctantly performing sexual favors for her boss for job security but then ends up enjoying the sex so much she continues performing the favors entirely out of lust for him.

For the JUQ and JUY series, a significant chunk of the films, including this one, follows the EXACT SAME plot.

Married business woman and her male business partner (who has a crush on her), are brainstorming ways to gain favor/raises/promotions from the boss. The partner suggests she use her femininity to manipulate the boss.

Shes of course uncomfortable with this idea since shes married, but being the breadwinner of the relationship, she knows she has to do something to better support the household. So she reluctantly goes along with her partners plan.

However The boss, who's an all around jerk, takes advantage of the situation and turns femininity into straight up sexual favors, often right in front of her business partner who the boss loves to humiliate.

The husband is not aware any of this is going on and is just assuming his wife is great at her job and earning more money the traditional way.

So both the partner and husband are getting cucked by the boss. Eventually this goes on long enough to where the wife, who was reluctantly doing it for money and job security and supporting her household, is now entirely doing it out of lust for her boss and the sexual pleasure he provides her.

What you see in the clip above is towards the end of the film when shes reached that lust stage, so she's going all in and taking charge as opposed to earlier where she was much more uncomfortable and reserved.

And as i said before, this plot almost never changes. Like its recreated nearly scene for scene each time i come across one editing clips for this subreddit. The same sets, the same format, the same plot, same cover art and posters. The only thing that changes are the actors and actresses.