Honestly I cannot believe no one made this recommendation sooner. 1st thing I told all my buddies after seeing episode one was if claymore and mamoru had a kid it would be freezing. All three have rediculously powerful female characters that transcend the normal limits of their world's understanding. Likewise all three main heroines have a significant relationship with a male character that becomes significant to the heroines fate in the story. Freezing is kind of balence for the other two. Where Claymore has the intense combat scenes, Mamoru focuses on the heroines inexperience with men and trying to overcome that with her first love.
Mamoru is mainly a school setting slice-of-life comedy with a touch of softcore ecchi.