Tsukuyo Inaba serves as a member of the Supreme Five Swords vigilante group at the Private Aichi Symbiosis Academy, enforcing discipline among students. The youngest member, she skipped a grade due to her prodigious abilities, making her the only non-high school student in the group. Despite her age, she holds the reputation as the strongest and most feared swordswoman among the Supreme Five Swords, with other members acknowledging her superior combat skills.

Her appearance features very pale skin, long white-silver hair tied in high pigtails adorned with a ribbon bell on the left side, and perpetually closed blood-red eyes. She typically dons a white shoulderless miko shirt with oversized sleeves featuring red stitches, layered over a sleeveless collared white shirt with a maroon tie. This is paired with high-waisted red hakama pants, a red sash around her waist, white socks, and black-and-red clogs. A set of bells on her head aids in environmental navigation.

Tsukuyo exhibits a calm, serious, and levelheaded demeanor, often providing detailed explanations during combat or observations. She becomes visibly upset when others ignore her advice or warnings, frequently expressing frustration with the phrase, "I’m disappointed." Beneath her composed exterior lies underlying loneliness and social uncertainty. She directly asks Nono if they are friends during a confrontation, accepting the affirmation with quiet determination. Her interactions with Fudou Nomura reveal emotional vulnerability; she experiences flustered reactions after he saves her from Kirukiru Amou and later questions whether their connection constitutes friendship.

A practitioner of Yakumaru Jigen-Ryū Iaijutsu, Tsukuyo specializes in lightning-fast diagonal slashes and precise strikes, capable of bisecting a flying butterfly with a training sword. Her blindness is compensated by hyper-acute hearing, allowing her to detect distant movements, analyze fighting styles through sound, and pinpoint locations—even identifying Nomura’s concealed presence in a bathhouse despite silencing efforts. Enhanced reflexes and speed enable rapid combat maneuvers, often leaving opponents unable to perceive her sword draws. She later masters an upgraded "Madan" (Magic Bullet) technique, surpassing Nomura’s original version, leading her to become his instructor to refine his abilities.

Her development involves pivotal battles. During a confrontation with Amou, Tsukuyo’s attacks prove ineffective against Amou’s hardened body, resulting in injury until Nomura intervenes. This event catalyzes her emotional openness and eventual mentorship of Nomura. Post-canon narratives depict her involvement in team-based missions: aiding against emotionless entities in Aichi, participating in orientation at Vanguard Academy, confronting DES soldiers in Neo-City, and attending memorial services for allies. Her social growth is reflected in defensive actions to protect Nono as a friend and collaborative efforts within Team Nomura during multiverse storylines.

Notable limitations include vulnerability to environmental challenges due to blindness, such as failing to detect Nomura’s physical exhaustion during their planned meeting at a fountain, resulting in her waiting in cold weather and falling ill. While her hearing allows navigation in familiar settings like the academy, unfamiliar or dynamic terrains present difficulties.