Just jumping right in, both actors were good; they were good at looking like they were in love... they just didn't look like they were in love with each other. I guess we could call that a lack of chemistry, but I associate that with having poorly portrayed a role which is not the case there, just felt... like they could have easily been acting to have been in love with a tree across the way, Takara. Again, his acting is good, it is just completely without regards to Tashin.
Also, the story would have been very good if it was better portrayed. If I wrote a summary of the story here, it would sound good! I just kept getting distracted by trying to sense any attraction between the two leads. Also, not to sound callous, but the whole mourning the bird? Yes, I was devastated when I lost my closest pet. I cried like Taishin did. But in a drama for general consumption? It is just cringeworthy. Tashin insisting over and over that Takara saved him when he was mourning the bird... I could just feel the awkwardness pouring off the actors. I could just feel Takara's actor being like, "I really have to act this scene out with a straight face?"
So, in conclusion, I could almost sense a good story if I ignored the actual presentation of the drama itself.