A lot of fountain pen fans especially love Japanese fountain pens, so there must be something different about them, right? Well, yes and no. There are things that tend to be different, and features you see much more often on Japanese pens. And some of those people might just love specific brands that happen to be Japanese.
And it’s not just fountain pens - the same goes for other types of Japanese pens. Ballpoints, rollerballs and gel pens all tend to have finer tips in Japan, with some extra-fine tips only rarely being available outside Japan. The main reason for this isn’t just a matter of taste - Japanese writing uses quite intricate characters, so writing them in small spaces requires a smaller tip size to fit them in. And to an arguably greater extent than in the West, a handwritten note is seen as a more personal thing.
So Japanese fountain pens, and pens from other Asian countries, generally have finer nibs than Western pens - so a Japanese ‘medium’ nib is likely to be finer than, say, a German ‘medium’. But there’s not set rule for what ‘fine’, ‘medium’ and ‘broad’ actually mean, so it can vary. And there are Western pens that are made in Asia, and even then, some might use nibs from Germany. But in general, a Japanese brand is likely to have a finer idea of what any particular size of nib means.
It’s also more common for Japanese brands to offer more unusual nib types. Platinum, for example, offer ‘music’ nibs; while Sailor also have their special ‘Zoom’ nibs (which write different widths when held at different angles).
For simple ballpoint pens and rollerballs, the same tip sizes we have are usually available, but in Japan, there are often even finer tips too, with the big brands competing to make the pen with the narrowest line width.
Japan also has a culture with great respect for craftsmanship, often passed down through generations and taking many years to learn. In pens, this is often found in special barrel designs, using techniques like Maki-e, where patterns or pictures are built up with tiny pieces of glitter or shells, set into layers of natural Urushi lacquer.
Another thing that varies between brands and specific pens, but is a general tendency, is that the Japanese market is more likely to see a lightweight pen as a sign of quality, where in the West, a heavier pen is more likely to be seen as being better. So Western pens may use extra brass inside a pen to make it more durable, while Japanese pens are more likely to use tough but lightweight woods and resins. Which you prefer is entirely a matter of taste.