Some offices have stereotypical dynamics: the chauvinistic pig of a boss who never does any real work; the employees whose goal is to suck up to the boss; the ones whose lives seem perfect; and the individuals who have all the actual work pushed onto them. Retsuko the red panda is in the last group, as she stays late most nights to make up the work her coworkers are too lazy to do themselves. Her relief from the stress of her everyday life comes in the form of singing death metal at a local karaoke club. Night after night, Retsuko channels her grief into a microphone and considers the place to be her own personal sanctuary. But as she moves further away from her comfort zone and the ideas people have of her, she discovers that letting others into her world of death metal may not be such a bad thing.

Red panda Retsuko continues to work at her cyclic office job, with the occasional stress-venting via death metal karaoke on the side. With the company of her newfound friends Gori and Washimi, life is more enjoyable than ever before. But some new shake-ups to her status quo threaten to add more stress to her life. At the office, new employee Anai seems like a fine addition to the company. Yet when Retsuko is placed in charge of his training, she finds that beneath his steadfast dedication, he may pose a threat to the stability of the workplace. Meanwhile, at home, Retsuko's mother pays an abrupt visit, fully intent on having her daughter finally settle down and find a man. With this in mind, she sets Retsuko up for various marriage appointments, much to her chagrin. Now, Retsuko finds all the more reasons to head to the karaoke bar and unleash her furious diatribes. However, knowing that this will not truly solve her problems, she decides to make a more spontaneous choice to avoid her issues. And so, Retsuko finds herself set upon another self-reflecting journey, coming to learn more about herself and love, with the ever cathartic support of death metal karaoke.

After an emotional breakup with her boyfriend, red panda Retsuko closes herself off to the thought of ever being in love again—well, with an actual person anyway. Retreating into the world of VR, her virtual boyfriend showers her with praise and shows up in cute outfits, albeit for a price. While scrambling to find other ways to earn money, Retsuko finds herself in yet another financial bind after accidentally ramming into a parked van with a rental vehicle. The owner of the van, a gruff cheetah named Hyoudou, recruits her as an accountant for an underground idol group which he manages. Retsuko soon begins to buckle under the pressure from the new job, leading to plenty of inspiration for her next death metal vent sessions. In the midst of it all, Retsuko begins to wonder if she truly desires a colorless and uninteresting life, or if there's something waiting beyond her office desk. Will Retsuko finally come out on top, both in love and in the workplace? Or will she once again be convinced that the dull and sterile life in her office environment is the one she must lead?

Fourth season of Aggressive Retsuko.