Yuuho and Jun are sisters. This is not publicly acknowledged; they themselves are both independently aware of it, but never discuss it until the events of Volume 4. They are the only known shinyuu pair to be related by blood.
As agnate siblings, they have the same father (Shizuma Eisei) but were born to different mothers, Jun to the wife of Kuga Gen, Yuuho to Shizuma Nami, and so were raised under these two different names. Mirroring the historical relationship between the Kuga and Shizuma families, Jun is heavily protective of Yuuho, sometimes calling her "Princess."
- Fought unnamed-students Pair. Heaven Sword won. WIN
- Fought Kurogane/Mudou Pair. Earth Sword lost. Heaven Sword's strike declared invalid. DRAW
- Fought unnamed-students Pair at Volume 16. Earth Sword won. Heaven Sword won. WIN
- Fought Takizawa/Imai Pair. Time expired. DRAW