Hikaru Shindō is the protagonist of the story, a boy whose life is transformed by an unexpected encounter. Physically, he is an average-sized young man with distinctive green eyes and short black hair that features unique blonde bangs. He is often seen wearing casual clothes or his school uniform, frequently with the numeral five on his clothing, which is a visual pun as the Japanese word for five, "go," shares its name with the board game that becomes his passion.

At the beginning of his journey, Hikaru is a completely ordinary and somewhat lazy sixth-grade elementary school student with no clear direction or serious interests. He is short-tempered, outspoken, and prone to blurting out his thoughts without considering the consequences. Initially, he finds the game of Go tedious and thinks of it as an old-fashioned pastime. His only motivation for playing is to appease the persistent ghost, Sai, who is trapped in an old Go board, and he is briefly enticed by the potential monetary rewards of becoming a professional player. This careless attitude changes drastically when he meets his rival, Akira Toya.

Hikaru's motivations evolve profoundly throughout the story. His initial foray into Go is merely as a vessel for Sai, but a crushing loss to Akira, who dismisses him as a weak player, fuels a burning desire to improve his own strength. His goal shifts from pleasing Sai to being recognized by Akira as a worthy opponent on his own merits. This rivalry becomes the central engine of his growth, pushing him to abandon his carefree attitude and dedicate himself fully to mastering the game. He joins a school Go club, trains as an insei (a professional Go apprentice), and eventually takes the grueling pro exam, all driven by the need to prove himself.

Throughout this journey, Hikaru's relationship with Sai, the ancient Go master, is fundamental. At first, he sees Sai as an annoyance, but he gradually comes to rely on his mentor's skill and wisdom. Their bond deepens into a powerful friendship, though it is also a source of inner conflict as Hikaru struggles to emerge from Sai's shadow and develop his own identity as a player. His rivalry with Akira Toya is equally significant. Akira, a prodigy who has dedicated his life to Go, is initially captivated and then infuriated by Hikaru, mistaking Sai's power for Hikaru's natural talent. Their dynamic is one of mutual respect and intense competition, pushing each other to greater heights.

As the story progresses, Hikaru matures significantly. The selfish, impulsive child transforms into a determined and serious young athlete. He develops a deep respect for the game and for the passion of other players. He learns humility through defeat and gains an understanding of the immense dedication required to succeed. His emotional range, from fiery frustration to quiet contemplation, becomes more nuanced as he faces the pressure of competitive play and the complexities of his unique situation with Sai.

In terms of ability, Hikaru's greatest asset is his latent, immense talent for Go. He possesses an extraordinary ability to read the board and calculate sequences of moves far into the future with incredible speed. His playing style is often described as unorthodox and unpredictable; he has a knack for making seemingly foolish or reckless moves that lure his opponent into a trap, which he then exploits for a decisive advantage. This intuitive and aggressive style sets him apart from players who rely solely on established patterns and conventional strategy, making him a uniquely challenging and formidable opponent. His journey from a complete novice to a one-dan professional player in just a few years is a testament to his natural gifts and newly forged determination.