Marufuji, Shou

Shou is a former Osiris, then Ra, and now Obelisk student as well as Juudai's best friend. A decent duelist, though hindered by a great deal of self doubt, Shou's journey toward strengthening himself provides sharp contrast to protagonist Juudai's active determination. Shou is often a "comic relief" character, partially due to him being very nervous a large portion of the time, in a sharp contrast to Juudai's optimistic nature.

(Yu-Gi-Oh! Wikia)