Mahou Shoujo Erena

Plot
With the help from a mysterious creature, Elena turned herself into a magical girl to beat Zoid, a tentacle monster to save her sister, Emile. Since that day, to protect her sister and to keep peace on the earth, Elena started to fight against the ugly creatures as a magical girl. However, what awaited her is a harsh destiny: immoral days of naughty humiliations. And her battle eventually involves her sister and her dead mother...