Sayaka Miki

Official Info

Madoka’s classmate and good friend. Energetic and lively, which is perhaps why her sword is the only melee weapon among the four.
Ms. Aoki’s Design Check!: Her personality is so boyish that I had to be careful not to make her look too boyish too. So I gave her hair a diagonal line in back, to straddle the line between short and medium length.
Magical girl outfit: Sayaka’s outfit is the closest to combat gear. Since her sword is a melee weapon, I paid attention to that while designing her clothes. (Aoki)
Her outfit features diagonal-cut skirt and shoulderless top for ease of movement. Add a cape, and she’s a picturesque swordswoman.
School uniform: Her figure is flat and plain, but her chest is bigger than Madoka’s. Her hairbow is a stitched design. Below, she wears simple navy-blue high socks.

The first character in her last name (美) means "beauty". The last character (樹) means "tree". Her name could also be written 幹 (tree trunk) or 神酒 (sake offered to the gods).
Her first name is written in hiragana, which has no special meaning. However, "sayaka" could also be written 明か (obvious) or 清か (clear).
She describes herself as having been born "Petit bourgeois." which is French for "petty bourgeois" or, essentially, middle class.

Many fans believe Sayaka is the witch in Madoka's dream at the beginning of Episode 1. More information about the theory here.