|Ally Type:||BOARD Member|
|Season:||Kamen Rider Spade Warrior|
|First Appearance:||Episode 1|
|Last Appearance:||Episode 33|
|Number of Episode Appearances:||33|
Rosalind Sidney is a twenty-year-old woman, whom is one of the few remaining BOARD members after it was attacked by the released Undead. She helped the Riders by detecting the Undead on her Undead-searching computer. She seems to care for Ray very much.
She had experienced in detecting Undead since she worked in BOARD. She also possesses superhuman strength as Rosalind is able to lift a refrigerator only with a finger much to both Ray & Kent's fright. Her father, Zachary Sidney, is the person who was responsible for breaking the Undead's seal in a fit of madness, dying in the process.
Near the end of the series, Rosalind was trying to prepare for her marriage but when a new threat surfaces, she decides to put aside her ideal life & helps the Riders once again by revealing the true identity of Albino Joker Undead. She was last seen celebrating Ada's birthday at the Jacaranda Cafe.
- Shiori Hirose - Kamen Rider Blade counterpart at Kamen Rider Wiki