Sena Kuroi functions as a recurring manga assistant to main artist Yūki Aito. Dubbed a "super assistant" for her exceptional speed and efficiency in meeting deadlines, she commands high rates and selectively accepts assignments based on her mood. These skills emerged from rigorous practice to overcome early professional hurdles.

Physically, she stands 140 cm tall with a youthful appearance frequently mistaken for childhood, featuring blonde hair and green eyes. Born December 10 under the Sagittarius sign, she is 19 years old.

Initially, Sena hides her affection for sweets, cute items, and small animals to evade perceptions of childishness or unprofessionalism. She gradually lowers her guard with those who treat her kindly, specifically developing romantic feelings for Aito over time. Her personality merges professional assertiveness with concealed vulnerability; she displays sadistic tendencies when disciplining Aito for inappropriate conduct, yet her physical strength remains notably weak—struggling with basic tasks like opening ink bottles, which previously forced her to quit assistantships from embarrassment.

Character development reveals emotional growth: she exhibits jealousy as a "clingy jealous girl" toward Aito and shows childlike behavior, particularly when intoxicated (easily induced by minimal alcohol). A pivotal arc involves her attempt to confess her feelings in the sequel manga, though this storyline stays unresolved following the series' cancellation.

Her interactions include bonding with cats through "cuteness proximity," and one incident where she disrobes to bathe them while drunk—during which Aito, despite his typical perversity, avoids exploiting the situation.