Kokoro Inogashira is a student of Class 1-D at the Tokyo Metropolitan Advanced Nurturing School. She has shoulder-length brown hair and yellow-gradient violet eyes. On the first day of school, she was the second student to introduce herself to the class, immediately following Yosuke Hirata. Her introduction was rushed and she could not help but stutter due to her nervousness, which left her feeling deeply embarrassed.

Kokoro is a neurotic and notably timid girl. She is inherently shy and becomes easily flustered in social situations, especially when forced to speak in front of others. Her reserved nature is reflected in her quiet hobbies; it is known that she enjoys sewing in her spare time. This preference for solitary activities aligns with her anxious personality.

As a member of Class D, the class considered the lowest tier within the school's strict meritocracy, Kokoro does not stand out as a leader or a major instigator. Instead, she represents the quieter, more passive segment of the class. Her primary motivation within the story appears to be the simple desire to avoid conflict and trouble, getting by in the highly competitive environment without drawing unwanted attention to herself. Her role is that of a background supporting character who contributes to the diverse dynamic of Class D.

In terms of relationships, she is a classmate of the main characters, including Kiyotaka Ayanokoji, Suzune Horikita, Kikyo Kushida, and Yosuke Hirata. She does not have a prominently featured close friendship or rivalry with any single character and generally remains on the periphery of the main group's activities. Significant personal development and notable abilities beyond her sewing hobby are not highlighted in the series. Her defining characteristics are her acute shyness and anxious disposition, which distinguish her among the other, more confident or driven members of her class.