Similar dynamic in both shows were the ML is human and the FL is a supernatural creature. Initially, both ML encounter the FL by breaking a curse / awakening them from another realm. If you like one, try the other.
Same "loser" MC with a girl with special powers that just shows up out of nowhere and rocks his world i suppose. The themes in both shows are quite similar even though Youkai GF is more action heavy. Similar shows, try the other if you seen the latter