Yui Higashiyama is a director working at a web production company. Since joining the company due to past trauma, she has been working zero overtime. In an environment where it's difficult for her to leave the office without a reason, she pursues efficiency more than anyone else while working, works with high productivity, and leaves the office at the appointed time. However, with the arrival of her new manager, a bunch of crooked employees stand in Yui's way. Workaholic Yui's ex-fiancé Kotaro Taneda; Toru Azuma, an inefficient man who lives at the company; Yasuto Kurusu, a new boy who wants to quit; Kanako Mitani, a woman with perfect attendance at work; Yae Shizugatake, a working mother raising twins, and Seiji Fukunaga, a manager who makes a series of negative remarks without any malice. How will Yui deal with the various problems faced by these people?

Yae Shizugatake, who is Yui's senior and was in charge of her education when she was new, returns to work after giving birth to twins and taking childcare leave. After returning to work, Yui and other employees around her can't hide their dismay when they see that Shizugatake has become too active. Meanwhile, the members of Production Department 4 won a competition and were entrusted with a PR project for a major beverage manufacturer's first visit to Japan. Shizugatake becomes the director, but trouble occurs just before the site is released. Meanwhile, Shizugatake's husband Yosuke informs her that the twins have a fever. Yui meets Shizugatake, who is struggling to balance childcare and work.

Yui was on her way to Takumi's parents' house to say hello, when Kotaro sent her a video that appeared to have been taken during the filming of a Firestrong commercial, and it went viral on social media. Yui remembers how Kurusu was filming with his smartphone at the filming location, and she calls Kurusu many times, but his calls go unanswered. The next morning, she blames Kurusu for coming to work as if nothing had happened, and immediately after that, Kurusu calls Yui and submits her letter of resignation.

Fukunaga hears from Marusugi, the managing director of Net Heroes, that an employee of the Production Department 4 is working unpaid overtime. While Yui and Kotaro are talking in the office, Kodama notices how Azuma is spending late nights at the office as if she were at home. Yui and the others call Azuma over and point out her unnecessary unpaid overtime and inefficient work style, but she can't seem to fix it. Meanwhile, temporary designer Sakuramiya arrives to help with a new project. Azuma is worried about Sakuramiya, who treats her cheerfully and kindly, and wants to show Sakuramiya a good side, so she consults Yui about how to improve her work efficiency, but at that time, trouble occurs.

One day, members of the Production Department 4 are called by Lander with an urgent requirement. Yui and her friends are at a loss when they are told that the design for the 20th anniversary site, which was supposed to have been approved the other day, doesn't quite work out. A few days later, when Azuma calls him outside, Soka from Lander is there and shows him a video of Sakuramiya running with Nakanishi and others wearing revealing uniforms. Yui is furious after hearing this and heads to Lander for a meeting, but...

After hearing rumors of Kotaro's independence, Yui and other members of the Production Department 4 become curious about his future. Meanwhile, it's decided that Kurusu will make his directorial debut with a new project, but things don't go well. Meanwhile, Yui takes Takumi to the Shanghai Hotel and reports her marriage to Wang Dan and others. Then, by chance, Kotaro comes along.

When Kotaro drunkenly says that he still loves Yui, she's speechless. Kotaro suddenly begins to sleep on the spot, ignoring the Yui and Takumi who are frozen. On the way home that day, Yui suddenly receives a call from her father who tells her that her mother has run away from home. Meanwhile, a new project from Fukunaga that doesn't fit the budget comes to Production Department 4.

A project marked with an asterisk that is bound to be in the red somehow manages to pass a strict internal review. Shizugatake is appointed as the director, and the members of the Production Department 4 proceed with their work under a strict budget and schedule that requires overtime. Meanwhile, Shizugatake receives a call from her husband, Yosuke, saying that her mother has collapsed, and Yosuke suddenly decides to return to Kumamoto alone. Shizugatake remains in Tokyo and struggles to raise twins and work alone. Meanwhile, Yui and Takumi seem to be going well after living together, but due to an unexpected incident they end up fighting.

Yui is suddenly summoned to the conference room by Fukunaga and is told the real reason why Kotaro quit his company. Meanwhile, while she is working on a project that's bound to be in the red, she comes across Fukunaga and the members of the Production Department 4 working unpaid overtime without Yui's knowledge. Meanwhile, Yui and Takumi begin preparing for their wedding, but as Yui's work becomes busier, their misunderstandings increase.

Yui is at a loss when Takumi tells her that they can't get married. Meanwhile, the outsourcing company goes bankrupt, leaving the members of the Production Department 4 in a predicament. Furthermore, Kotaro is summoned from the Star Factory and is required to remove Fukunaga from the project as a condition for proceeding with the contract. After hearing this, Yui finally confronts Fukunaga, but will she be able to protect the team?