Gorou Sasabe is a former student of Iwatobi High School and was once a member of its swim club. In the past, he served as the coach for the local Iwatobi Swimming Club, where he taught a young Haruka Nanase, Makoto Tachibana, Nagisa Hazuki, and Rin Matsuoka. After that club disbanded, Sasabe found work as a pizza delivery person. Despite his career change, his passion for swimming and coaching never faded.

Sasabe has a kind and friendly demeanor, getting along well with his students and understanding their strengths and weaknesses. However, when he steps into the role of a coach, he becomes strict and demanding, earning him the nickname Goro the Demon. He is not afraid to push the swimmers hard, correcting their form, kicks, and timing, and he sometimes expresses frustration when they seem lost. His coaching methods are practical and effective; for example, he uses recording equipment to allow swimmers to analyze their own techniques from multiple angles. Outside of the pool, he has a more relaxed and easygoing side, often seen wearing Hawaiian shirts and shorts.

Motivated by the renewed enthusiasm he sees in the teenage boys he once taught, Sasabe is driven to help them succeed. Even though he already had a part-time job and coached without pay, he dedicated himself to preparing the Iwatobi High School swim team for their relay competition. His commitment runs deep; in Free! Eternal Summer, he makes a significant sacrifice to provide the team with a proper training facility. He sells his grandfather’s old squid fishing boat, which he was entitled to, to buy back and rebuild the old, nearly bankrupt swimming club, reopening it as Iwatobi SC Returns.

In the story, Sasabe serves as the primary coach and mentor for the Iwatobi High School Swim Club, as well as the owner-operator of the revived Iwatobi SC Returns club. He is a reliable adult figure who provides guidance, facilities, and unwavering support for the main characters’ competitive swimming goals. His role becomes even more crucial when the school’s own pool is unavailable, forcing the team to rely on him and his refurbished facilities.

Key relationships center on the main group of swimmers. He shares a strong bond with Haruka, Makoto, Nagisa, and Rei Ryugazaki, acting as their coach and a trusted confidant. His history with Rin adds another layer, as he coached Rin as a child and later supports his competitive endeavors. Sasabe also has a unique, humorous relationship with Miho Amakata, the school’s homeroom teacher, as he discovers she was a gravure idol he admired in his youth, a fact she prefers to keep secret.

Sasabe undergoes notable development from a former coach working an unrelated job to a dedicated, full-time coach and business owner. His decision to sell his family’s boat to resurrect the swimming club represents a major turning point, demonstrating his immense dedication and willingness to sacrifice his own assets for the sake of the swimmers’ dreams. This act cements his role not just as a trainer, but as a passionate guardian of the local swimming community.

Beyond his coaching abilities, Sasabe has several notable practical skills. He holds a boat license, allowing him to operate his grandfathers fishing vessel, a skill that occasionally proves useful in helping the team with aquatic logistics. His experience as both a competitive swimmer and a coach gives him a sharp eye for technique and race strategy.