He once assumed the identity of Dai Moroboshi (諸星 大 , Moroboshi Dai) and infiltrated the Organization, where he was given the codename Rye (ライ ).
His superior is James Black and his partner is Jodie Starling.
He had infiltrated the Black Organization under the name Dai Moroboshi - and the codename "Rye" - as a mole and dated Akemi Miyano, one of their low-ranking members, to feed information to the FBI.
In order to facilitate the latter, and later because he had genuinely developed feelings for Akemi, Akai saw himself forced to break up his then on-going relationship with Jodie.
Later on, his cover in the Black Organization was accidentally blown by his colleague Andre Camel, and when Akemi was killed, he declared her murderer, Gin (with whom he seems to have had some tensions even before his exposure), his personal enemy.
Five years prior to the current time-line, FBI agent Shuichi Akai infiltrated the Black Organization using the alias Dai Moroboshi as a mole and dated Akemi Miyano, one of their low-ranking members, in order to meet Shiho Miyano and use her influence to get into the Black Organization.