Nodoka Haramura is a first-year student at Kiyosumi High School in Nagano Prefecture and a main protagonist in the Saki series. She began playing mahjong during the fourth grade while staying in a hospital, and her family moved frequently due to her mother's work assignments. She lived in Nara for a time, where she attended Achiga Girls' Academy and befriended Shizuno Takakamo, and later moved to Nagano, where she met Yuuki Kataoka at Takatoobara Middle School. During middle school, she won the National Middle School Individual Championship, gaining significant media attention that often exaggerated her skills. To stay with Yuuki and continue playing mahjong, she chose to attend Kiyosumi High School despite her father's initial reluctance.

Personality-wise, Nodoka is pragmatic, serious, and deeply logical. She firmly believes that mahjong is a game of skill rather than luck, and she dismisses supernatural explanations for players' abilities as coincidences. This rational mindset sometimes puts her at odds with teammates who rely on instinct or chance, such as club president Hisa Takei. Despite a reserved demeanor that can come across as cold, she cares deeply for her teammates and shows a supportive, loyal side. She is also notably afraid of darkness and thunder.

Nodoka's primary motivation is to win the national high school championship, both to prove herself and to honor a promise made with her teammate Saki Miyanaga. She also aims to validate her decision to stay in Nagano and pursue mahjong despite her father's disapproval.

In the story, Nodoka serves as the vice-captain (fourth position) on Kiyosumi's mahjong team. Her role is critical to the team's success, especially during the national tournament arc (Saki: The Nationals). She is a key player whose analytical style keeps the team competitive against opponents with more unorthodox abilities.

Her key relationships include Saki Miyanaga, whom she initially resented for surpassing her skill but later grew close to, forming a deep bond and mutual promise to reach the nationals together. She shares a long friendship with Yuuki Kataoka, who helped her adjust to life in Nagano. She also has a supportive dynamic with senior Hisa Takei, who helps Nodoka overcome her distractions in live play by recommending she use a stuffed penguin named Etopen to maintain concentration. Additionally, she has a history with Shizuno Takakamo, a former friend from Achiga who later works to face Nodoka in the national tournament.

Nodoka undergoes significant development over the series. She starts as a proud, competitive player who feels threatened by Saki's natural talent, but she learns to accept and trust her teammates, transforming her from a solitary competitor into a cooperative and supportive team member.

Her most notable ability is her performance as the online mahjong player known as "Nodocchi." Under this alias, she has a winning record that surpasses most professional players, making rapid, complex decisions with minimal errors. In live matches, however, she tends to be distracted by her surroundings, which reduces her efficiency. Hisa's advice to use Etopen helps her simulate the focus she has online. Nodoka's refusal to acknowledge supernatural elements in mahjong is itself a notable trait, as it shapes her straightforward, probability-based playstyle and sometimes leaves her vulnerable against opponents who rely on unorthodox methods.