Yes, she is Japanese, she acted in Love Letters as well with Kim Jae Won and Kim Rae Won. But she did not need to have any dialogue becos she is a mute in that k-drama.
On www.yesasia.com, most of the KBS serials comes with subtitles. E.g. 18 yr old bride, Snow White. But SBS and MBC are not so diligent about Eng subtitles.
But there are loads of resources on the web. I get a lot of my info from www.soompi.com as there are alot of k-drama fanatics that does translation for series. So you can still buy your non-sub ones and perhaps read off the translations.
Also, try this bit torrent site for Eng sub k-drama by k-drama fanatics
http://www.d-addicts.com/forum/torrents.php
I love that volcano scene! The way LBH looked at SHK from afar in that out fit, it is to die for that gaze! If you don't want spoilers, then read my review only after you finish this series.