Both series have a non-human female lead who just likes to hang out with the male lead and troll him a little. The male leads in both series were somewhat similar too. If you liked one of those series, odds are you like the other one as well.
All Shinta wants is to find a girlfriend, and constantly falls in 'love at first sight' with his classmates. Unfortunately for the boy, none seem to reciprocate his intense feelings, and thus, he does the only thing he can think of – he visits a local shrine to hopefully have his wish granted. Much to his surprise, Shinta encounters a god at the shrine who decides to grant his wish, and the next morning, Shinta wakes up next to the lovely goddess Isana. But all wishes come at a price – it's that time of year when gods throughout the world battle it out for territory, and each deity like Isana must use a human as their champion. Now, Shinta must fight countless enemies for his newfound girlfriend, even though she doesn't seem to want to give him the time of day!
A goddess finds herself a human companion and together they fight umm... things. Both series are plenty fun, so if you liked one, make sure to read the other one as well.
Did I mention that the goddesses in both series can take several forms?
Both manga feature a girl who transforms back and forth between a loli form and a teenager\adult form. In both series for the girl to transform into her original form she has to kiss her loved one.