I didn't expect a very bold action on 1st episode. It surprised me that someone ( writer) came up with this story line. Very brave and unusual.
Plot twist at the end makes my heart broken.(*Because I always in a K-drama plot) This drama turns me to think seriously about Love and sex from Japanese point of view. It's kind of different from what I believe, but then I realized they're just high school students. And this kind of thing is happening for real somewhere.
This drama teach you to let go of something what doesn't belong to you in a worse way and also in a good way.

I like this drama because it's uncommon story. When you getting bored with k-drama love story, this drama is surely something new.
But be careful there is a lot of Mature content in each episodes.
A little bit boring in the middle but it's not that hard to finish it.