Satsuki Kiryuin is the powerful student council president of Honnouji Academy. It's assumed she's in control due to her mother's will.
Satsuki Kiryuin is the main antagonist of the Kill la Kill anime series that was produced by Trigger. It's directed by Hiroyuki Imaishi and written by Kazuki Nakashima. The character design was done by Sushio. The series first began in October 3, 2010.
Satsuki's rule over Honnouji Academy stood unchallenged from any true opposition as she spread her will and the will of the Kiryuin Clan throughout the nation. That was until a drifter name Ryuko Matoi appeared wielding a Scissor Blade and looking to challenge her and learn who killed her father. She appeared to be no real threat until she returned from her initial defeat wearing a kamui she called Senketsu. Time and again, Ryuko defeated her Student Council members to get to Satsuki.
After finally having had enough and angered someone would beat her to the punch of donning a kamui, Satsuki stormed into her family's home to claim her Junketsu. In-spite of her mother's will, Satsuki unsealed Junketsu and gained its power. Satsuki's first test of this new power was put against Ryuko the very next day. She grossly outclassed Ryuko up until she had finally synchronized with Senketsu. From that point on, the battle was far more evenly matched.
The battle ended in a draw, but Satsuki made a deal with Ryuko. If she could defeat all the members of the Honnouji Student Council, they would have another rematch. Only then would Satsuki tell her what she so desperately wanted to know.
The Bakuzan is Satsuki's cherished sword. It's unknown where she gained this katana, but she is almost never seen without it. Her power with this sword was even greater that Ryuko's with her kamui.
Junketsu is a kamui, a type of school uniform made of 100% Life Fibers, that Satsuki Kiryuin wears. He was created by the Kiryuin Organization specifically for her when she was a child. Her father called it her "wedding dress". However, he was eventually sealed away and she was forbidden to use it by her mother. This still didn't stop her from claiming it after she was challenged by Ryuko in Senketsu.
Though it normally appears to be white school uniform, it can transform into an incredibly powerful suit of armor that boosts her strength and speed. The cost of this power is that he needs to draw out Satsuki's blood.