 If you liked
Toaru Majutsu no Index
|
 ...then you might like
High School DxD
|
Fantasy works that draw on mythology and religion heavily, incorporating those into their power system. Both have harem undertones but the protagonist isn't the usual wimpy one harems tend to have, but a man of action. What started off by the main character accidentallying himself into some sort of scheme late turned into the protagonist getting involved in various situations to protect what is dear to him.