Gekkō is a pale girl with silver grey long hair and green eyes. She wears a gold and black suit composed of a white vest and a yellow jacket, both sleeveless, with a black apron on top of them, both in front and behind her. She has yellow sleeves detached from her vest, with black losange plates. She has long yellow pants-things on top of yellow boots. The moon croissant symbol is found on several part of the outfit.
Like her half-sister, Senkō, she pretends to be a perfect student in Middle-School and is thus admired by her schoolmates, through that side of personality is mainly a facade to hide her true personality.
Being the friendly half-sister of Senkō, Gekkō is known to have a most likely positive, tough and kind personality, even through she isn't less fanatic and brutal in term of way to achieve to her objectives. Driven to Justice, she felt along her sister empty until she found Kurokage's diary hidden in the school's library, discovering his extreme ideals of Justice, which she made hers with her sister. It's only after losing to Yumi that she adopted Kurokage's "New" Justice.
Senkō is her half-sister. They work as a pair and plan together.
In the beginning of the New Link anime series, she ambush with her sister and capture all of Hanzo team except Asuka that they leave in a torn clothing, openly contradicting her ideal of Justice. When they lose the Shinobi Masters, and after Hanzo team was freed, they presented their excuses to them for their brutal methods.
They found Fubuki by following Kurokage diary's indications on mountains, and presented themselves to her as his admirators, thus Fubuki took care of them and directed them to destroy all shinobies.
At the end of the Shinobi Masters, Fubuki abandons them after they put doubt on her methods. They try to fight her once, ending up on a clear defeat, stripped, and try to soften Fubuki at the very end by both touching her hand, but end up knocked out by her Yoma nature.
Yumi fought and defeated them with Asuka at the end of the Shinobi Masters. When they attempt suicide in a river due to feeling abandoned and seeing that their ideals of justice were wrong, Yumi held their hand in sorts to explain her justice.
Gekkō was with her half-sister the archetype of the perfect middle school student, even having influence at the Student Council, and are admired by their schoolmates. Actually, they felt lost, without any goal, and found by some hasard on Kurokage's diary hidden in the library, in which they discover his manichean and murderous ideals, and adopt them. Following the diary's indications, they travel to the top of mountains to find Fubuki and present themselves as Kurokage's admirators, making that Fubuki take them as her henchwomen. From that point, they obey to Fubuki's instructions thinking that they were protecting and favoring Justice in the Shinobi world.
Gekkō starts in the New Link anime by ambushing the Hanzo team with her sister and ask them about Shinobi Justice. Hearing about the "Sword and Shield" idea, they show their contempt of such naive ideal and capture all members of the team except Asuka, which they leave in torn clothing by Fubuki's order to leave alive so she can tell the terrible story of Shinobies.
They send arrows to all the other teams (Crimson Squad, Gessen, and Hebijo) to invite them to a free day at the baths, and present themselves once all of them finish an improvised PBS in the baths, inviting to a special shinobi tournament, the Shinobi Masters, and announcing that the winner will free the Hanzo team members, all kept as hostages. Only Hebijo, Gessen and the Overseers' festival, which were invited by Fubuki after a short fight with Kagura, join the tournament, the Crimson Squad having refused due to an incident with Homura and Asuka which left Homura injured at the wrist.
Once the Overseers and Hebijo are defeated, they face Yumi and Asuka as the final challenge, but end up defeated and stripped. When Fubuki declares war to all shinobies, they're abandoned there by her. Later, they lunch on Hanzo's roof and present their excuses to the Hanzo team, through the team is very sympathetic about it, and they both get groped by Katsuragi.
When Fubuki launch a Yoma invasion in the town, Gekkō and her sister attack directly Fubuki and ask her explanations, but they get defeated. Feeling abandoned by everything, they get near a river and a cascade, remind their lives and try to jump in the water before Yumi finds them and grab their hands to show them her justice.
They are last seen at the end of the fight between Yumi and Fubuki, grabbing the latter's hand to correct her by showing Yumi's justice, but they get knocked out by Fubuki's Yoma nature and power.
- Gekkō's name (月光) means "Moonlight".