Emilio Lowe is Chrono Number III, and did not appear in the manga but they did mention number 3 once in a conversation.

Chronos Number III, Emilio rarely appears in the Anime, mainly in the final part of the story, on the final attack on Creed's base on Clarken Island. After the defeat of Creed, he reveals himself as one of Mason's Zero Numbers, on the Eden project.

Source: Wikipedia