Owning and handling watches from other brands that compete against GS, the Grand Seiko gets all the tiny details so spot on. All it takes is a close look at the dial, hands, indices, and you'll see the magic. Here's a photo I saw over on another watch forum that shows what I'm talking about.
There's such an extreme attention to detail, and the Japanese pursuit of perfection shows in the product IMO. The level of care in the manufacturing process is impressive as well, with movements being fully assembled by either a single watchmaker, or a team of two. GS's heat blued seconds hands are done one at a time, not in batches. They have someone assigned who only oversees the bluing of seconds hands to make sure they're right on. Cases are indeed completely finished by one person, by hand. In my experience, GS has really deep, defined graining in their case brushing, and it makes the polishing stand out all the moreso. Dials have printing applied one at a time, not in batches. If you see the printing for "Grand Seiko" on one of the dials, it has this raised effect and appears glossy. They get this by using a special gelatin pad for applying the printing. It's pretty cool to see.
I can pass on a video for you, showcasing Grand Seiko's manufacturing processes if you'd like.