Momoko Mochizuki is a college student and a classmate of Renji Kusakabe in the university setting of Cultural Exchange With a Game Centre Girl. She grew up in a family-run kendo dojo, which gave her a strong physique and formidable self-defense skills that she carries with quiet confidence. Her initial curiosity about Renji stems not from romantic interest but from an uncanny resemblance he bears to her childhood dog, a nostalgic connection that draws her attention. On the surface, Momoko projects a warm, easygoing presence reminiscent of a caring older sister, and she often acts as a grounding, local perspective for the cross-cultural interactions unfolding between Renji and Lily Baker. Her personality is spirited and energetic; she can be loud when excited and is not afraid to wield authority when the situation calls for it. Despite her forthright demeanor, she is generally supportive and curious about the cultural exchange happening around her. Momoko’s role in the story is that of a supporting character who appears in group settings and school-based scenes, facilitating social interactions and offering commentary on the central pair’s developing relationship. She maintains a friendly, classmate-level bond with Renji and develops a cordial acquaintance with Lily through their shared campus life. Her character arc is largely static; she does not undergo major personal growth but instead serves as a reliable fixture within the protagonists’ social circle, helping to ground the narrative in a typical Japanese university environment. Notable abilities include her kendo training, which manifests in her physical strength and reflexes, though these skills are rarely showcased in the peaceful setting of the game centre and campus.