Like Tengu, Flengu has wild shaggy hair that trail down to his feet, carries a leaf fan, and has tengu-geta on his feet. His hakama is colored blue, his shirt lavender-ish in hue, and his skin a dark tan in hue.
He is apparently known to cause droughts in order to punish humanity.
Flengu's fire alignment and tendency for punishing humanity might be a reference to karura, a humanoid bird creature related to the Hindu legendary birds called garuda. It generates flames that scorch the sinful, and it gives its name to the fiery halo surrounding Acala, the fierce-eyed Buddhist god that smites the wicked. Karura are a stock character in gigaku plays, and are believed to be a prototype for the depictions of tengu (see Tengu#Origin).
"Flengu" is a contraction of flame tengu, which is also the translation of his Japanese name (Japanese: 炎天狗,Japanese name).