User blog comment:FairyRaven/Fairy Tail Chapter 347: Red, Blue, Blond Hair Fight! Review and Commentary/@comment-2214433-20130816143856/@comment-7418318-20130816144858

There were only two actual hostile demons in the story so far, Deliora and Lullaby (let's disregard Hades' rubble demons here, since they didn't seem to be living magic and fell apart once he lost the demon heart).

Deliora fell apart and obviously dead, but Lullaby returned to being a flute, so my bet goes for Lullaby.

The Succubus' Eye mage might be a partial (or complete) demon, but with an absence of just once chapter it's unlikely that the chater is named after him.

Maybe one of the Galuna Island demons makes a return, possibly following the treasure hunters after they obtained their liquid Mood Drip from there. If that's the case I guess it'll be Bobo (the "fisherman" that brought them to the island), maybe accompanied by the village chief Moka.