Warning: the following contains spoilers for My Senpai is Annoying Episode 6, "Grandpa Hearts Futaba," now streaming on Funimation.
In My Senpai is Annoying, Futaba Igarashi has been working hard to make a name for herself at the office, and has managed to make plenty of supportive friends and co-workers who care about her. Still, Futaba doesn't like being patronized or treated like a child, and it's not just her co-worker Harumi Takeda who annoys her, but also her boisterous biker grandfather, Mr. Igarashi, who arrives in Episode 6.
Futaba loves her grandfather, but she also wants to succeed in life and her career without needing her overprotective grandfather watching her every move and trying to fight her battles for her. When Mr. Igarashi arrives in Tokyo, not puts not only Futaba on edge, but Takeda as well, finding a new rival in Futaba's Grandpa.
In My Senpai is Annoying Episode 6, Futaba and Takeda realize that they share the same birthday, and so they exchange bouquets as gifts at a florist. That's when Futaba's grandfather, the tough-talking Mr. Igarashi, arrives on his bike, outraged that Takeda got Futaba a gift before he could. At once, Mr. Igarashi becomes overly protective of his granddaughter, and he and Takeda butt heads over who is more important in Futaba's life, and who should really be her #1 defender and fan. The two men argue over beers later, while an exasperated Futaba tries to fathom their unbelievable levels of obnoxiousness. When Mr. Igarashi and Takeda cross paths again later, they resume their verbal battle at once.
Later, Futaba spends her day off with her friend Natsumi, causing Mr. Igarashi to panic when he can't reach her. He imagines Futaba on a date with Takeda, and takes it upon himself to get between them and understand Futaba's heart better. Mr. Igarashi doesn't make any real headway, but he tries his best anyway, even going to watch Your Name in theaters, which at least proves how diligent and caring he can be. Even if his protective feelings are misplaced, Mr. Igarashi takes his granddaughter's safety and happiness seriously, just as much as Takeda does, if not more so. But that's not enough to stop him from kicking up their feud again, though they finally talk things out in the evening.
Mr. Igarashi explains Futaba's backstory and makes it clear that, even as a teenager, Futaba was a headstrong and independent person who didn't want to rely too much on others and become a burden. To Futaba, being coddled isn't just annoying, it also denies her a chance to prove to everyone, including herself, that she can look after herself. Futaba identifies strongly with her independent streak, and sis proud of her self-sufficiency. Mr. Igarashi and Takeda both deeply admire this about her, and bond over their mutual respect for Futaba. The feud ends, but their protective feelings remain.
Later, a trio of punks start harassing Futaba, until Takeda and Mr. Igarashi intimidate them, uniting as a team to keep Futaba safe. The punks flee, but Futaba is grateful for the help. Beyond that, she's happy to see her grandfather and co-worker getting along at last, and the three of them decide to eat out together, proving how far they've come in just a few days. Nothing will stop Takeda and Mr. Igarashi from worrying about Futaba, but they can restrain their feelings somewhat and let Futaba live her life without a pair of helicopter parents casting too long a shadow over her. They finally find some balance.