anti-art attachment
対魔術式駆動鎧 アンチアートアタッチメント Tai_Majutsu-shiki_Kudō_Yoroi Anchi_Āto_Atatchimento A.A.A. AAA
Power suit from the ToAru Majutsu no Index series.
The Anti-Art Attachment (lit. "Anti-Magic-Type Powered Suit"), A.A.A. for short, is a Powered Suit (ToAru) developed in Academy City and used by Kihara Noukan. As the name suggests, it is for use against magic, though despite that, the suit has a connection with magic, specifically that of Aleister Crowley. Also commonly used by Misaka Mikoto.
External links
https://toarumajutsunoindex.fandom.com/wiki/Anti-Art_Attachment