if you go and watch the credits for the Sealed Sword Frenzy, Aizen, Gin, and Tousen show up in the end in casual clothes. You might also want to take a look at the artbook and color chapter spreads, Kubo likes to put a lot of characters in regular clothes for those.
2013 Con Schedule:Japan Expo, PMX?
Kuroko Tetsuya (Kuroko no Basket)COMPLETE!
Alibaba Saluja (Magi: The Labyrinth of Magic)COMPLETE!
Hige (Wolf's Rain)COMPLETE!
Sanada Yukimura, Revoltech limited edition variant (Sengoku BASARA)COMPLETE!
Subway Master Nobori (Pokemon Black&White)COMPLETE!
Candlehead (Sugar Rush!/Wreck-It Ralph)COMPLETE!
Scrafty (Pokemon Black&White)COMPLETE!
Hatsune Miku, Magnet variant (Vocaloid)COMPLETE!
Skull Kid (Legend of Zelda: Majora's Mask)