Shalba Beelzebub

Shalba Beelzebub (シャルバ・ベルゼブブ Sharuba Beruzebubu)

Decendant of Beelzebub. He was the one that forcefully activate Issei's Boosted Gear's Juggernaut Drive and was defeated because of it but manages to place a curse on Issei as a final act.