Shirakami Shimatsu

A mysterious Puella Magi with an unknown history, Shirakami Shimatsu is somehow tasked by a mysterious magical girl (no, not Ultimate Madoka) to travel many timelines to save the Magical Girl's many alternate reality counterparts. Unknown to her, she actually bears the title of "Destroyer of Timelines".

Abilities & Powers
She also has the ability to clean soul gems, however if she absorb too much grief, she would turn against her allies.
 * Destroyer of Worlds - Her main weapon. A metallic gold-coated rifle, named "Destroyer of Worlds", which can transform into two modes: Rifle & Sword. The gun also had a symbol "VIII (Eight)" crafted on the gun's left. However, she also had multiple powers from other Puella Magi: like:
 * The 8 Puella Magi Powers:
 * Pink: Arrow & Bow
 * Purple: Time-manipulation
 * Yellow: Muskets/Ribbons/Tiro Finale
 * Blue: Swords/cutlasses
 * Red: Spear/Cloning
 * Grey: Vine-patterned Spheres
 * Pale Orange: Large, curved claws
 * Other Puella Magi Powers:
 * Shining Light - Used during in the Final Episode.

Complete Form
If Shirakami had collected 8 Puella Magi powers, she can assume the ability called "Complete form", However if she had only 5 powers obtained, her form is dubbed as "Half-complete form"

Half-Complete form
She can activate them via her will power, The armor changes into a new one, and her chest armor changes too. The main 5 slots contain the soul gem symbols of Madoka, Homura, Mami, Sayaka, & Kyouko.

She also can summon the 5 girls, as soild holographs. They can attack the witches via command or their will. Shirakami can also use the ultimate power called "Trump Card Finisher", which commands the 5 Magical Girls (Along with her ultimate shot)  to finish of a witch with their attacks (for example: Madoka's ultimate arrow, Homura's multiple bazookas, Mami's Tiro Finale, and the KyouSaya Formation (which is the formation between Sayaka and Kyouko's sword & spear thrust)) in one time. This was similar to Kamen Rider Diend Complete Form's Final Attack Ride.

Trivia

 * She is an homage to the three characters:
 * Ultraman Ginga & Rockman X: using multiple powers, and the parts change color corresponding to their forms.
 * Kamen Rider Decade: also tasked to help the character's alternate reality counterparts, and also bears the "destroyer of worlds" title.
 * Her costume somehow bears a resemblance to the White Wizard from Kamen Rider Wizard.
 * Her name: Shirakami, is based on the two words: Shiro (White, 白) & Kami (God、神), and her name Shimatsu　（始末）, is based on the word: Beginning to the end.
 * Her face resembles Akemi Homura, as said by Ultimate/Normal Madoka.
 * She also resembles Oriko Mikuni, as said by Kirika Kure.
 * It is unknown if she had a witch form, since she was a different type of Magical Girl.
 * It was speculated that she was the late Oriko Mikuni, because of her white colors & her prophet like clothes. This was false.
 * Her weapons from the other Puella Magi is based on Hanokage's weapon designs.
 * She is referred as:
 * "The White Time Saver".
 * "The White Wizard"
 * "The Mysterious White Puella Magi"
 * Her both forms (Nightmare, Magical Girl) from the movie is also similar to Sou Fueki, which he was both Wiseman & White Wizard.
 * Her bottom part of the Magical Girl outfit resembles the early production sketch of Akemi Homura.
 * In one of the omake manga strips, she was revealed to be tryphanophobic. However this isn't canon.