Mazoku no Jikan

From MangaHelpers:

The magical world of monsters has lost their fight with the humans, and they've since been leaderless. Then, they voted for a new ruler, the zombie Addy. Addy may not be the fighting type, but with help from her butler and the sorceress who summons her first small 'army' of monsters, she'll do her best to fight the humans! This comedic 4-koma follows Addy's life as she takes on her new role as the demon king. [tethysdust]