Masako Araki is the coach of Yosen High School's boys' basketball team in Kuroko's Basketball. Before becoming a coach, she was a successful youth basketball player who earned a place as a regular on the Japanese women's national basketball team. This high-level playing experience gives her a deep understanding of the game and a sharp strategic mind. She is a mature woman with long black hair and shaggy bangs that cover her forehead, paired with dark-blue eyes. She is most often seen in a black suit with a white collared shirt underneath.

Araki is known for her strict and no-nonsense demeanor. She is a tough coach who does not tolerate laziness or insubordination, and she is not above physically disciplining her players with a shinai when they slack off or misbehave. This intimidating presence makes her feared by many of her players, yet she earns their deep respect because her tough love is rooted in a genuine care for their development. She combines strategic brilliance with a fiercely competitive spirit. A background detail sometimes noted in supplementary material is that she had a past associated with a biker gang, which contributes to her rough, no-nonsense attitude. Beneath her severe exterior, she fosters a strong sense of faith in her players's abilities.

Her primary motivation is to lead Yosen to victory by molding her talented but sometimes unmotivated players into a disciplined and effective team. Her role in the story is as the commanding authority figure for Yosen, one of the major rival teams. She is responsible for managing and directing two of the series's most prominent players: the immensely talented but lazy center Atsushi Murasakibara, and the skilled but conflicted forward Tatsuya Himuro. Her relationship with Murasakibara is defined by her constant efforts to push him to take the game seriously, a task that often tests her patience. With Himuro, she acts as a mentor who recognizes his dedication but also holds him to a high standard. Araki is also acquainted with Kagetora Aida, the coach of Seirin High School, as they knew each other from their time in the national basketball scene; there are hints in light novel material that she may have had a crush on him, though he treats her like a younger sibling. Her development is subtle but clear: while she remains a stern taskmaster, her moments of quiet encouragement and her fierce protectiveness of her team reveal a deeply caring side that her players come to rely on. Her key ability is her tactical acumen, allowing her to design game plans that maximize the strengths of Yosen's tall and powerful roster.