The Witch's Servant and the Demon Lord's Horns(2014)

Majo no Geboku to Maou no Tsuno

Arsenio, the loyal servant of a witch, receives an order from his master, and this one won't be easy. He is to retrieve a horn from the Demon Lord himself! But once he infiltrates the Demon Lord's castle, his expectations are immediately subverted: the Demon Lord appears nothing more than a mascot, and Arsenio catches him harassing a young, shapely girl...?! Will Arsenio be able to squeeze out a victory? Or is something else getting the squeeze first?

(Source: Manga UP!)

Note: Includes 1 extra chapter.