Bllan was a humanoid demon covered in a thick layer of oozing slime, that hung loosely from his body and limbs, he had two tentacles in place of his eyes and a large wet smile.
After the young Akira Fudo donned the mysterious Demon Mask at the behest of his friend Ryo Asuka, he is suddenly bombarded by visions of demons. Among them was the demon Bllan, who could be seen standing at the top of a large crowd which included Naza, Somerci, Sirene, Tolios, Lamicabuja, Worat, Ijam, Monan, Eizar, Tillag, Kagol, Olsat, Xeed and many others.
He briefly makes a second appearance in another large group compilation as Ryo explained the origins of the demon race to Akira.
Much later on, after Sirene had been badly wounded in a fight with Akira, she begs to Zennon for help. In response he summons a small army of lesser demons, among which included Bllan. Alongside several other demons, he attempts to attack Akira, but quickly gets himself decapitated instead.