Acqua of the Back (後方のアックア Kōhō no Akkua?), real name William Orwell (ウィリアム＝オルウェル Wiriamu Oruweru'?), is a character introduced in Toaru Majutsu no Index. A strong and willful man, he is a mercenary of renown in England, and originally a Saint of terrific power. He was a member of God's Right Seat, and is one of the few characters who easily defeated Kamijou Touma in combat. After the events of World War III and the dissolution of God's Right Seat, he is once again referred to using his real name.