Anime Picture

Oga is usually seen sporting a grosteque grin and his demonic features are visbly shown when he is either angry or distrubed. He posesses brown hair and dark eyes, he is rather muscular with a wide-spread build, and his attire usually consists of a worn-out shirt and plain pants (usually jeans). He has been shown on a few ocassions to be wearing either sweatpants, and on one ocassion, has even been shown wearing his pijamas (ironically very detailed with pinstripes going down the side). When Oga attempts to smile, he is usually seen with a demonic, evil grin. This speaks to his lack of social skills (due to his ihibition in a juvenile highschool).

When fighting Oga appears to have a different look. Aside from his rare comedic entrances (usually relief from an intense situation), he is usually very calm and actually quite aware. His eyes are alert and he seems in control of his emotions. Be'el does not transfer this emotion however, and is usually shown in a maintained angry look.

source : www,beelzebub.wikia.com