Higano Tadashi, who works at an advertising agency, is an ordinary employee in the Sales Section 4.

Sales Section 4 boasts the highest performance in the department and is known as the company's star department, with beautiful women, including the section manager.

Tadashi is one of the few men in the department, and is considered to be in a somewhat enviable position within the company, but in reality he is treated as a burden to the department. He is cursed at by the section manager and chief almost every day, and is looked upon with scorn and ridicule. He is even mocked by the temporary assistant he is paired with.

The only person who supports Tadashi as he endures these humiliating days is the chief's assistant, Shirahama Kanade. She is an angelic woman who is the only one in the department who treats Tadashi kindly. Just having her smile on his face makes Tadashi happy, and he is determined to do his best even in this situation.

However, one day at the end of the year, he is cruelly informed that Shirahama Kanade is getting married.
"Shirahama-san is getting married and retiring at the end of this fiscal year. Her partner is our department chief, Hayama-san."
When Yui hears the name of the man who had been the one who bullied him and sees Kanade blush with happiness, he feels as if the ground is crumbling beneath his feet.

The tragedy doesn't end there. Having somehow pulled himself together and tried to switch his mindset to celebrate her happiness, he is walking during his lunch break, when he overhears a conversation between the female department staff in the cafeteria.
"That useless bald guy, it was obvious that he had feelings for Shirahama-san."

"He always looks at Shirahama-san with that weird look in his eyes and smirks. It's really creepy, I thought about reporting him for sexual harassment. You must have found it creepy, Shirahama-san?"

"You shouldn't say that much."

"Again, no one is listening, so be honest."

"...To be honest, it was creepy."

Realizing that even the woman he had trusted up until then was just like the others, Yuji decides to take revenge. He will completely trample on their dignity and make them understand their status as sex slaves.
And ultimately, he will destroy the entire department.
Before the New Year holidays, Yuji begins to draw up a plan...

[Translated from the official site]