Senna

茜雫

Senna is a young girl with purple hair adorned with a red ribbon. She has large, orange eyes and is typically seen wearing a brown school uniform. When she transforms into a Shinigami, Senna wears the standard unseated shinigami uniform, featuring a large, red ribbon tied around her waist.
Senna likes the color red and high places. She is also very curious, constantly darting from place to place. Although she is haunted by brief, randomly-appearing memories of "her" past, Senna generally exhibits a spunky, upbeat, and carefree personality.
As stated by Ichigo, Senna is additionally strong-willed, stubborn, loyal, and somewhat outspoken.

Spoiler

Senna also has Shinigami powers and a Zanpakutō. Rukia reveals her Zanpakutō was lost 100 years ago in the Severed world. However, it wasn't revealed as to how Senna obtained her Shinigami powers or her Zanpakutō.
Besides her Zanpakutō, and ability to control Blanks, Senna has shown to be skilled in swordsmanship, and an agile fighter and gymnast. Even in her gigai, she is very agile, able to perform several backflips at once. It is implied she is adept in Flash Steps when she falls and seemingly disappears, reappearing behind Ichigo during a tight-rope walking performance at the Karakura Mall, fooling even Ichigo, who is an expert in Flash Steps himself.
Zanpakutō
Mirokumaru (弥勒丸, Maitreya circle)
Shikai: Her zanpakutō is released by the command "Call forth the Twilight" (夕闇に誘え, Yūyami ni izanae; "Bring them to the twilight" in the English dub). It takes the form of a Khakkhara when released.
Shikai Special Ability: Mirokumaru has the power to create and control tornadoes.

Spoiler