Very similar premise (both involves time warping, someone who has the ability to cause time warping, meeting people from the past etc.) , both based on a top selling novel, and both are touching and well acted!

There are many similarities between the shows, ie:
-Grumpy male lead with a heart of gold hidden under protective layers of absolute douchiness
- Rich to poor female lead with a smile that's brighter than the sun
- The better guy overall second lead (at least before the male lead softens)
- and many more pre-2015 kdrama tropes.