I've followed Japan and Sylvian since ca 1980 (I used to play Polaroids/Quiet Life to death over the speakers in the record shop I was working in at the time).
And I am probably the only one on here who found Blemish a disappointment.
I just found "Blemish" too bleak and too foggy when it came out; I get the sense of loss and breakup, but it just does not touch me.
Tthe last time I listened to it I still felt the same.
I will pick it up again one day and see if I can see the light, but for me the standout track (Late Night Shopping) and the artwork are the best bits.
For a breakup album I'd much rather listen to Marvin Gaye's "Here My Dear".
Tin Drum is the pinaccle of Sylvian, now he seems to have gone the same way as Bill Nelson, a soul with enough dosh to get by and looking for guidance in mysticism and religion while releasing introspective musings. I went the whole hog with Bill (well I jumped off around 1990 after losing interest) and Dave seems to be going the same way as Nelson (ie obscure soundtracks or ballet/theatre/installation music).
You might as well start with the Everything and Nothing collection for an intro (even if it overlaps with the "real" releases there are tracks on there that is not elswhere and it covers a lot of ground). The Hansa collection "Assemblage" is a good intro to the pre Tin Drum stuff (the only LP sampler available at the time, but seems to have been re-issued endlessly with different extras/tracklistings on CD). For the instrumental works try Camphor, but listen before investing.
The Rain Tree Crow release is worth getting as well as his contributions to other people's works (ie Sakamoto, Virginia Astley, Fripp, Sandii&the Sunsetz etc).
(and if anyone's got a Laserdisc player I still got "Oil on Canvas", but never seen it. The idea was to get the player, but before I got the player the technology had died).
Might be worth having a look at this list as well -
http://www.nightporter.co.uk/pages/newdiscog.htm