Kazuki Sendo is the main protagonist of Comic Party, a young man whose life changes dramatically when he is introduced to the world of doujinshi, or fan-made comics. Before this introduction, Kazuki is portrayed as a somewhat indifferent and directionless student. He has a natural talent and passion for drawing and painting, but his abilities were once deemed insufficient for admission to a formal art school, leaving him feeling adrift in his college life. It is his enthusiastic, and often overbearing, friend Taishi Kuhonbutsu who brings him to the massive Comic Party convention, sparking a new purpose in Kazuki's life.

Personality-wise, Kazuki is defined by a strong work ethic and a genuine, kind-hearted nature. While he may initially seem like a bland and unassuming everyman, this allows the more eccentric personalities around him to shine. However, beneath this ordinary exterior lies an intense and driven passion for creating manga. Once he commits to making doujinshi, he dedicates himself to it completely, often to the point of neglecting his personal life and his relationship with his childhood friend, Mizuki Takase. He is not naturally ambitious or cunning; rather, he is often pulled along by the schemes of Taishi and the demands of the doujinshi community, though he genuinely comes to love the act of creation. He has a notable fondness for sweets.

Kazuki's primary motivation shifts over the course of the story from simple curiosity to a profound desire for self-expression and creative integrity. Initially convinced by Taishi to form a doujinshi circle called Brother 2, Kazuki handles the artistic duties while Taishi manages the logistics like printing and licensing. His early works are influenced by parodies of existing series, but he gradually develops a commitment to original storytelling and artistic authenticity. Even when faced with commercial pressure or the offer to become a professional manga artist, his core drive remains rooted in the joy of drawing and connecting with fans, valuing substance and personal expression over mere popularity.

Within the story, Kazuki serves as the emotional anchor, navigating the chaotic and passionate world of otaku culture. His role involves countless late-night drawing sessions, stressful trips to the printer, and the challenge of selling his works at conventions. He experiences the highs of success and the lows of seeing his creations fail to sell, learning valuable lessons about the market and his own artistic goals. A significant part of his journey involves a rivalry with the popular but shallow Eimi Ohba, which forces him to confront his own definition of success as an artist.

His relationships are central to his development. The most important of these is with his childhood friend, Mizuki Takase. She initially disapproves of his foray into the otaku world, viewing it as a waste of his talent and a threat to the life she envisioned for them both. Her opposition creates a major source of tension, but her eventual acceptance and support are crucial to his growth. In the end, their relationship matures as they reconcile his passion for manga with their life together. His friendship with the relentless Taishi is the catalyst for his entire journey, and he receives guidance and support from other female doujinshi artists like the experienced Yuu Inagawa and the shy but talented Aya Hasebe.

Throughout the series, Kazuki shows clear development. He begins as a disillusioned college student who failed to get into art school and transforms into a determined and confident artist. He learns to balance his creative ambitions with his personal relationships, ultimately forging his own path that honors both his love for manga and his connections to the people who matter most. His journey is one of perseverance, facing creative blocks, physical exhaustion, and personal sacrifice to pursue his newfound calling.

In terms of notable abilities, Kazuki possesses a strong, natural talent for drawing and illustration. He has a particular skill for painting, which is his original artistic love before entering the world of manga. His ability to quickly improve and produce popular work under intense deadlines demonstrates a remarkable capacity for hard work and adaptation. An unexpected and humorous talent revealed in the animated adaptations is his surprising mastery of cross-dressing, which he uses to a startlingly convincing effect. He also has a creative imagination, which leads to a storyline where he bands together with another character to form a group of crime-fighting superheroes called the Comi Rangers.