are malevolent creatures believed to originate in Gehenna
. They seem to be lesser in ranks than the Devils
that also inhabit this plane
Demons are encountered in many of the games, but especially noteworthy is The Legend of Heroes: Trails in the Sky The 3rd, The Legend of Heroes: Zero no Kiseki and The Legend of Heroes: Ao no Kiseki in which they play a slightly more important role. Many manifestations of demons created by the Lord of Phantasma are fought in Phantasma.
Demons were regularly summoned by the D∴G Cult. It is also possible for a human being to become "demonized" by consuming Red Gnosis as was the case for Joachim Guenter.
There are some beings and objects referred to as "demon" such as the Vermillion Apocalypse and the Demonic Flute but whether or not they have their origins in Gehenna is debatable.