I actually have a karaoke sample of this song by Sing Like Talking included in the article for its album "Discovery", but I just had to get the real McCoy included when I found out of its existence. Yup, I think it's that good.
The video above has a shortened version of "Kokoro no Tobira" (The Door to your Heart) but it's still worthy of praise. As with pretty much all of Sing Like Talking's songs, it was written by keyboardist Chiaki Fujita（藤田千章）and composed by vocalist Chikuzen Sato（佐藤竹善）. Since "Discovery" was my first experience with SLT, it took me a while to get to know the songs in depth but "Kokoro no Tobira" was one of the first tracks to finally get me onto the bandwagon.
Whispery synths and the soulful vocals by Sato kinda label this as a romantic stroll of a ballad, and of course, I'm a sucker for a good flugelhorn. I would probably put it in as a good sunset or early evening tune. It's about as AOR a song that anyone will ever find in J-Pop and a fine introduction to the wonders of Sing Like Talking.