Kotoko Aihara is the main female protagonist of the romantic comedy anime Itazura na Kiss. She is introduced as a high school student who is cheerful, energetic, and outgoing, but notably lacks academic ability. Kotoko is often portrayed as clumsy, impulsive, and somewhat scatterbrained, which frequently leads to humorous situations. Despite her struggles with schoolwork, she possesses a resilient and optimistic personality, rarely staying discouraged for long.

Her primary motivation throughout the story is her deep and persistent love for Naoki Irie, a brilliant and cold-hearted classmate. After being rejected publicly by Naoki, a stroke of fate leads her family to temporarily live in the Irie household, giving her a second chance to win his heart. Kotoko’s actions are largely driven by her devotion to Naoki, though she also genuinely wants to improve herself and find a meaningful path in life, even if her grades do not reflect that effort.

In the story, Kotoko serves as the emotional core and the primary point of view character. Her journey moves from an unrequited crush to a committed relationship, marriage, and eventually motherhood. She often acts as a catalyst for change in Naoki’s emotionally distant personality, gradually bringing warmth and vulnerability into his life. Her persistence, loyalty, and honesty contrast sharply with Naoki’s intellect and reserve, creating the central dynamic of the narrative.

Kotoko’s key relationships include her father, Shigeki Aihara, who is a warm and supportive single parent and the owner of a small restaurant. After her mother’s death, Kotoko and her father share a close bond. Her relationship with Naoki Irie evolves from that of a rejected admirer to an eventual wife, though even after marriage she often feels insecure about his feelings. She also forms a close friendship with Kinnosuke Ikezawa, a kind and gentle classmate who harbors his own feelings for her. Kotoko’s interactions with Naoki’s family, especially his mother Machiko, who actively supports Kotoko’s pursuit of Naoki, are also significant.

Kotoko undergoes notable development over the course of the series. Initially depicted as a hopelessly poor student with little direction, she eventually trains to become a nursery school teacher and a nurse, showing a commitment to caring for others. While she never matches Naoki intellectually, she matures emotionally, learning to stand up for herself and becoming more confident in her role as his partner. Her unwavering love evolves from teenage infatuation into a more grounded, mutual support system.

Kotoko does not possess any supernatural or remarkable physical abilities. Her notable traits include her high energy, social charm, and an almost limitless capacity for perseverance. She is skilled at cooking and household chores, which she uses to express her affection, especially toward Naoki. Her greatest ability is her emotional resilience: despite repeated rejections, failures, and moments of doubt, she continues to pursue what she wants and to care deeply for those around her.