Makoto Tachibana's journey unfolds throughout the *Free!* series and related media. Childhood in Iwatobi forged a lifelong first-name friendship with Haruka Nanase, starting in kindergarten. Makoto initiated their shared participation in the local swimming club. A formative event occurred when a fisherman who gifted him goldfish drowned in a typhoon, instilling Makoto's thalassophobia (fear of the ocean). He tended a grave for the goldfish in his backyard, changing its flowers daily even after the fish died during sixth grade. Initially swimming breaststroke in competitions, he switched to backstroke during an elementary school relay, finding comfort in seeing the sky. This became his specialty stroke. His family includes parents and younger twin siblings, Ren and Ran, whom he frequently cares for, showcasing responsibility early on. Recruited for basketball in junior high due to his physique, he chose swimming instead, joining Haruka, Asahi Shiina, and Ikuya Kirishima. Another incident involved a stray dog following him home; Haruka named it Makkou and agreed to care for it when Makoto's mother proved allergic.

In high school, Makoto became a founding member and captain of the revitalized Iwatobi High School Swim Club. His leadership unified members and provided steady guidance, contrasting with Haruka's swimming skill but reserved nature. Makoto frequently interpreted Haruka's nonverbal cues, advocated for him socially, and restrained his impulsive behaviors near water. Despite his imposing stature, Makoto exhibited easily frightened tendencies, often hiding behind Haruka—a habit from childhood. During a training camp, Rei Ryugazaki got caught in stormy seas. Makoto confronted his ocean phobia to rescue Rei but nearly drowned himself, requiring Haruka's intervention. This forced him to confront his thalassophobia. His dedication included organizing logistics, mediating conflicts, and supporting members like Rei during lessons. As captain, he balanced nurturing relationships with competitive focus, especially in relay events where swimming with Haruka held deep meaning.

Facing uncertainty in his final high school year, coaching children at Iwatobi Swim Club Returns clarified his passion for teaching swimming. He decided to pursue sports medicine at Meijo Chuo University in Tokyo, aiming to become a professional sports trainer. This decision significantly impacted Haruka, contributing to a temporary rift resolved upon Haruka's return from Australia. After graduation, Makoto moved to Tokyo alongside Haruka, marking his first independent living experience. At university, he refined his career focus toward training competitive swimmers. He maintained close ties with Haruka, meeting for swimming or study support, and remained perceptive about Haruka's emotional state. Makoto reconnected with former junior high teammates like Asahi and Kisumi Shigino, sharing stories about Haruka and aiding efforts to mend Haruka's relationship with Ikuya Kirishima. During one confrontation, Makoto intervened when Haruka challenged backstroke swimmer Hiyori Tono, insisting on racing Hiyori himself to protect Haruka's freestyle specialization.

Makoto's personality blends kindness, consideration, and emotional sensitivity with underlying resilience. He consistently prioritized others' welfare, evidenced through caretaking roles for his siblings, Haruka, and younger swimmers. His gentle demeanor featured frequent smiles and patient encouragement, though he wearied of friends' eccentric behaviors. Deeply intuitive regarding Haruka's thoughts and feelings, their communication often occurred wordlessly. Makoto leveraged this understanding to motivate Haruka, sometimes using water-related incentives, though this became less effective as Haruka grew more independent. Their relationship featured reciprocal support: Makoto managed Haruka's social interactions and anxieties, while Haruka defended Makoto during fearful moments and walked nearer the ocean due to his phobia. Makoto uniquely used the nickname "Haru" or "Haru-chan." Physically, Makoto possesses a tall, muscular build with olive-green hair, green eyes, and notably developed trapezius muscles. His image color is green, and his motif animal is the orca. Personal preferences include favorite foods like green curry and chocolate, enjoyment of video games and sibling playtime, academic strength in literature versus struggles in English and art. His fear of horror stories or supernatural elements persists alongside his managed thalassophobia.