Even in the Senran Kagura series, some Shinobi don't belong to any faction, or only are members of a faction under certain circumstances, the rest of the time being alone or unaffiliated.
They can also be a duo of shinobi, being too few to be considered an actual group.
Failed Hanzō Admissions
Though somewhat affiliated with Hanzō National Academy through his family, he himself actually failed to be admitted and is not technically a member.
She Who Cleanses All Yōma / Guardian of the Reincarnation Sphere
This duo consists of Kagura, Destroyers of Yōmas, and Naraku the Guardian of the Reincarnation Sphere. Through they team up with the Mikagura Sisters in New Link and Shinovi Master, they are the rest of the time not affiliated with any faction.
Like A Flower in Full Bloom
- Sayuri / Jasmine
She leads the Overseers of the Festival in Estival Versus, and constitutes a boss in Peach Beach Splash.
Kagura Millenium Festival
Deceased elder sister of Ryōna and Ryōbi, she was revived on three or five occasions, one in Estival Versus, two in PBS, and eventually one in New Link and New Wave. Before dying, she was a member of Gessen Girls' Academy.
Peach Beach Splash
He never mentions his affiliation, though he is a shinobi himself.
These characters have school uniforms, but no known school or affiliation. They appeared as boss characters.
With collaboration projects between Marvelous and other companies, some characters are added and playable in certain Senran Kagura games. Coming from other series, those characters aren't attached to any faction in Senran Kagura.
Dead or Alive
- Ayane: Appears in both Estival Versus and Peach Beach Splash using the same emblem.
- Marie Rose: Appears in Peach Beach Splash, but using a different emblem from Ayane. Hers is a stylized rose.
- Honoka: Appears in Peach Beach Splash, but using a different emblem from Ayane. Hers is a stylized skull and cross bones.
The first three appear together in Estival Versus, while Ryomo joins them in Peach Beach Splash. Chō'un joins the other four in New Link. However, in their original series they represent different schools instead of being in the same faction.
King of Fighters
These two appeared in New Link, featuring a faction emblem with the letters "QB" on it.
High School DxD
These characters appeared in a Senran Kagura: New Wave collaboration and in Senran Kagura: New Link, featuring a faction emblem with a shield with a "K" that stands for Kuoh on it. Rias and Akeno appeared in New Link first, with Koneko and Rossweisse joining in a later crossover.