I have no idea why everyday cosplay=Halloween but apparently Japanese celebrate it this way.
AKB48 – Halloween night
They are cosplaying different professions and the concept for each member was decided by Akimoto Yasushi.
Jurina- Takarazuka
Takamina – Gyaru
Sasshi – Politician
Paruru – Nurse
Yukirin – Hostess
Tomu – Priestess
Sakura – Maiko
Sayanee – Sexy Secretary
Mayuyu – Waitress
KitaRie – Kindergarten Teacher
Yui – Cabin Attendant
Milky – Ballerina
Matsumura – Pro Wrestler
Akane – Music Station AD Intern
Shibata – Retro Idol
Yuria – Police
Shiritsu Ebisu Chuugaku – Super Hero
Denpagumi.Inc – Eikyu Zombina
Golden Bomber – The v kei ppoi kyoku
I think Golden Bomber are the only ones who got it right. They were the creepiest of the night.
Kyary Pamyu Pamyu – Pumpkin no Gyakushu
Nakashima Mika – Hanabata
I loved the CD version but this live is a major flop! Is this person really Nakashima Mika?!
TOKIO – Tokyo Drive
They are cosplaying as Tamori san.
AllThingsJpop 
Kyary seems kind of like she’s going through the motions on stage now.
Anyway, I love Mika’s new song, but that live performance was just terrible. I’m honestly a bit shocked at her vocals.