[MrTerrorist]

Chapter 2 to 4 of Maoyu Maou Yuusha Gaiden has been scanlated!

Spoiler for Gaiden ch2-4:

So we are introduced to Witch Girl's companion in this story, Feather Girl of the Singing Wings clan. Freeing her after defeating the Lord Wizard, a blue demon Birdcon (lol) whose been ripping off the towns people, Feather Girl decides to follow Witch Girl as her servant.

However, they are attacked by Red Mage, a witch that was trained by the Magical Association, which Witch Girl knows well. It turns out the Magical Association experiment and tried to create their own Heroes using children which left many dead except Witch girl, whose was also known as the Sliver Mage, as the only survivor. She was encourage by her late older sisters, White Mage and Indigo Mage to join Hero and his friends and leave the Magical Association to be free.

Red Mage was sent to the Demon world by orders of the Holy Father of the Church to kill Witch Girl and take her place because the Magical Association sees Witch girl as a failure since she not under their control. Refusing to allow a "fake hero" to threaten them and Hero, Witch girl manages to defeat Red Mage, forcing her to retreat.

While mending her wounds, Feather Girl reveals even though she has wings, it's a taboo for children to fly until they perform a ritual for their Goddess who will give them her blessings to fly. But Witch Girl points she doesn't need to do the ritual since her body is capable of flying. And then we find out why Feather Girl is following Witch Girl; she's the last of the Singing Wings clan so she doesn't know her clan traditions of the ritual. Feeling sorry for her, Witch girl allows Feather girl to follow her and heads to the Fairy clan's home.