Leonardo is a Human Assassin-Delivery Man from the North American server whose first appearance in the second season of the anime adaption was episode 14. A month after the Catastrophe, he fled from the Big Apple due to the riots and lynching after the discovery of Real Food Preparation and a subsequent attempt to monopolize the secret. After hopping into a Fairy Ring, he found himself in China, where he was eventually found and rescued by Kanami's Party, which he joins.

His Overskill is Parallel Plot.

(Source: Log Horizon Wikia)