Chained Soldier

In this world girls are gifted super powers by eating peaches, While guys are gifted nothing. This has caused a divide between the the two groups. However, these powers are needed in order to fight monsters called Shuuki that invade from a dimension called Mato. Not only do people die from the monsters crossing into earth, but people also go missing in what is now known as Mato Mishaps. On his way home from school Yuki Wakura is transported into Mato where he gets targeted by a Shuuki. Right before he is about to be attacked he is saved by a girl named Kyouka Uzen riding a Shuuki of her own. While they manage to get away they find a little girl that has also been caught up in a Mato Mishap, and while trying to defend her Kyouka loses her Shuuki. Seeing it as the only way out Kyouka asks Yuuki to be her new slave. When he accepts he transforms into a Shuuki like being. After defeating all the enemies in the area he is taken back to the base of the 7th Squadron of the Demon Defense Force. He stays there and agrees to be their caretaker while they aren't fighting Shuuki. Will Yuki have what it takes to defeat the Shuuki and protect those close to him?

Chained Soldier was better than I was expecting. However, there are ecchi scenes in each episode. The reason being is that whenever Yuki does his job as Kyouka's Slave the power requires that he be given a reward equal to his efforts. This comes in many forms like kissing with tongue, bathing together, letting Yuki stare at her body, etc. Anyway the story and world building are good. They also do a good job of making the characters grow on you in my opinion. If you don't mind fan service I would say that Chained Soldier is worth a try.