Kaoru Shiba (志葉 薫 Shiba Kaoru?) is the true 18th head of the Shiba House, a position that Takeru was holding in her place. She is referred to by her vassals and servants as Princess (姫 Hime?). As the head of the Shiba House, Kaoru is the one who possesses the knowledge of the Sealing Character (封印の文字 Fūin no Moji?) also known as the Gedou Seal (外道封印 Gedō Fūin?), a Modikara passed along the Shiba bloodline (the kanji is fictional, but is composed of the kanji for Mon (門?, "Gate"), A (亞?, "Sub-"), Ken (剣?, "Sword"), and Honō (炎?, "Flame")). Because of this, she stayed in hiding while Takeru acted as her kagemusha to draw the Gedoushu away from her. When she grows tired of living in hiding, she masters the Sealing Character to defeat the Gedoushu and assumes her birthright. Even though she is kind and easy to work with, she underestimates the vassals' dedication to Takeru, and when she is injured in attempting to use the Sealing Character, she adopts Takeru and gives up her birthright to allow Takeru to lead the Shinkengers in defeating Doukoku. She makes another appearance in Tensou Sentai Goseiger vs. Shinkenger: Epic on Ginmaku, combining her Mojikara with Alata's Gosei Power to create the Kaentornado card, which is used to free Takeru from his Gedou Shinken Red form, and allow all the Shinkengers to utilize the Super Shinkenger form.
In episodes 11 and 12 of Kaizoku Sentai Gokaiger, Kaoru appears in front of the Gokaigers, demanding to hand over the Shinkenger Ranger Keys to her. Instead, she is challenged to a sword duel by Joe Gibken, but the fight is interrupted by a Zangyack invasion. Seeing the heroic deeds of the Gokaigers - particularly Captain Marvelous risking his life to save Joe, Kaoru concedes her challenge and gives Joe a special Secret Disc that helps the Gokaigers unlock the powers of the Shinkenger keys.
Like Takeru, Kaoru is the Samurai of Fire and has the ability to become Shinken Red, referred to as Princess Shinken Red (姫シンケンレッド Hime Shinken Reddo?) to differentiate with Takeru's Shinken Red, and use the Inromaru to transform into Super Shinken Red. Her secret training allows her to easily adopt all of the weaponry the others had used before her appearance.