Goro Mori, age 14, is a close friend of Ko Ide and classmate to him and Hidomi. He is a bit of a comedy relief character in the beginning, but develops greatly in Stone Skipping. His subsequent appearances show him beyond this comedic exterior as a truly helpful friend desperately searching for companionship.
Goro is very outlandish and wacky, much like Gaku Manabe from the original FLCL series. He lies to his friends that he has a girlfriend. He believes in a unisex fashion trend and prefers to wear a skirt, which displeases Ide, along with colorful clothing, giving him a hippie-like appearance. However, he is stubborn in his beliefs and refuses to change. He is in love with Aiko to the point of hiring her as his pretend girlfriend, showing that he lacks confidence. He's also very jealous of Ide when it comes to women.
Goro is slightly overweight and is known for his weird clothing. He often wears bright colors, many of which clash, and tends to select questionable accessories. In class, he proudly wears a short skirt, which he claims is unisex and in with the current fashion trends. He has messy, buttercream blond hair parted at the center and thin blond eyebrows. His brown eyes are housed in white glasses
Goro's chivalry and determination becomes vital in Our Running. He becomes a guard to Aiko, who just so happens to be Mabase's last hope, as well as a bike chauffeur to her and Hinae during these dire straights.
In episode 3, Goro hires Aiko to be his pretend girlfriend in front of his friends. He often brags about, presumably, fake conversations with her in order to boost his ego whenever she's away and is very over the top with his gentlemanly behavior when she's around his friends. She keeps a shy demeanor on the job, but quickly switches to a crass and better-than-thou attitude when they are alone. Although Aiko is initially not interested in him, she eventually falls for him in the last episode after he helps her.
Ide is one of Goro's good friends, but he doesn't approve of Goro's fashion. Goro is very jealous of Ide's relationship success with their teacher, though Haruko was actually just using their time together to examine his N.O. capability. However, when Hidomi seems to fall for him and their lives become intertwined by Haruko's meddling, Goro finds himself crying, shouting at the ocean, and venting his frustrations toward the end of a beach outing when Ide is distracted by searching for Hidomi.
Marco is also good friends with Goro and respects his sense of fashion, or at the very least does not voice any opposition towards it. He lends an ear to Goro when he finds himself overwhelmed by Ide's new relationship, though he doesn't add anything.