Sekirei: Pure Engagement

Similarities: Both lead male character's (Minato and Muneakira) first kiss involves one of his harems falling from the sky (Musubi and Jubei). Both animes features a lot of panty shots and boobies. Both lead male characters always has someone in his harem that he fears the most. In both animes the one that is closes (Jubei and Musubi) to the male character is the most naive and ditsy, but had the most potential of all the harems. There were also the youngest in the harem that makes the male character look like a lolicon. In both animes it is the ladies that does the fighting for their lead male characters even if they are reluctant to allow them to (the ladies). Also, in both animes the ladies reach their full potential when kissed by the male character. Dissimilarities: One has more women in his harem that the other, however, one has more partial boob exposure and full panty shot that the other. One has caught 2 girls falling from the sky, while the other has only caught only 1. One has to watch out for 3 of the girls from his harem that he fears, while the other only has to watch out for the 1 who is the most jealous and his lady lady too (who is not part of his harem). One has a member of the harem which the lead male character is not sure he can trust,while the other one has a member of his harem who was a dude before,but turned babe which the male character was reluctant to kiss at first. One has 2 girls in the harem who were very young, one is flat chested but smart,the other is well endowed but stupid, while in the other anime the male character has only one who is very very young, adorable to all but very powerful.  read more 

One male created a harem of girls who fight for him and to power up the female warriors both male characters need to kiss the female character and both female character has a mark on them 

Kissing unleashes the power and stronger the bonds. The MC has the power to make up with girls. 

Girls that get powers from kissing