Kuretake Zig Letter Pen CocoIro Pen Refill - Super Fine - Cool Gray

Pros: Nice fine line, lovely bluish dove grey ink. "Extra Fine" really is EF. I imagine it works great for writing characters with many detailed strokes.

Cons: These pens (well, refills, but I use them just as pens) tend to get blobs of ink on the tip while capped, no matter how they're stored. On some papers, they take an extremely long time to dry completely. I seem to be using up the ink very quickly, sketching rather than writing.

YMMV: The pen holders look weird with the refill sticking out the back. I'm not sure whether the blobbing problem has to do with something like the heat/pressure from using the refills without a holder. If I were more motivated to test them, I'd experiment, but I don't care for the holders and I like a narrow pen, and this is working well enough.

Overall: I love this soft grey for sketching and for fine, small writing, and it hasn't blobbed yet. It's functional enough to get a middle-of-the-road, 3-star review.