Hokuto Itsumo is a second-year student and a key member of the table tennis club at Suzumegahara Middle School. Her family runs a table tennis specialty store, an environment that has given her a practical knowledge of equipment, from paddles to rubbers, and a notable sense of thriftiness when it comes to handling money. Physically, she has short, light blue hair that she often styles with a carrot-shaped hairpin, and she is most frequently seen with the collar of her jersey pulled up to cover her mouth.

Possessing a calm and introverted personality, Hokuto is quiet, analytical, and rarely speaks at length. Her signature trait is her highly calculative and defensive playing style. She does not rely on raw power or speed; instead, she uses pattern analysis to predict the most likely trajectory of the ball. This allows her to manipulate the pace of a rally, move into position before her opponent strikes, and send the ball to areas that are difficult to return. Her ability to read the game is so acute that she can even discern the type and color of a girl's underwear simply by touching her paddle's rubber. This peculiar skill leads her to give teammates nicknames based on their undergarments.

Hokuto's primary motivation within the story is tied to her friendship with Hanabi Tenka, a childhood friend with a much more energetic and offensive playing style. The two have known each other since they were young, and Hokuto often helped Hanabi at her family's ping pong store. Hanabi is one of the few people who can consistently break through Hokuto's reserved exterior, often causing the usually stoic girl to blush through hugs, clinging, or playful gestures like having her hair buns squeezed. While initially ranked third in the club, her development is linked to overcoming her overly predictable patterns. When facing players like the transfer student Koyori Tsumujikaze, whose adaptive and free-spirited style defies analysis, Hokuto is challenged to move beyond her calculated methods and discover new dimensions to her game. Her relationship with Hanabi also deepens through their doubles partnership, where their contrasting styles begin to complement each other. Despite her deadpan demeanor, Hokuto shows moments of excitement, particularly when watching Hanabi's determined expressions or competitive spirit.