Above: The tip of the new Tachikawa Linemarker A.T, 03 nib. The metal part of the nib is approximately 3/8 inch long. The full pen is standard length for such things, being a long, non-tapered cylinder, slightly less thick than the barrel of the Faber-Castell Pitt Artist's Brush Pen, and also slightly less long.
Since writing this post I have had time to work more extensively with this pen. My additional comments on the Tachikawa Linemarker A.T. can be found here. I encourage you to read that post when you are finished here.
Last Thursday I stopped over at Wet Paint to meet a friend (and look around). They had just received this pen. It comes in 3 nib widths: 01, 03, and 05, from thinnest to widest respectively. It uses a cartridge.
I had to buy one and bring it home to give it a full test (they have a tester model in the store). It is not as flexible as some fountain pens I've used, but it is more flexible than the Rotring Sketch pen. You can get some variation in the line, which is always pleasant.
Left: An oversharpened image (so you can see the paper texture) from my current journal, when testing this pen. My current 6 x 8 inch journal is made from Arches Text Wove which has a slight pebbly texture to it. In addition it floats ink on the sizing a bit. (You can read about this in my post "It's Not Waterproof until It's Waterproof.") Note the edges were cropped on the scan, but they aren't important. What's important is on the left side I got "bleeding" that was slight and most of what you see is blue paint on the brush! On the right on a thinner line, where two minutes later I actually had to scrub hard to try to get it to bleed and it didn't. (Two minutes is a guestimate as I was writing notes and such and decided to test another area. Again, it's within the realm of when you might go directly to painting if you had finished a sketch and were working your way around a drawing with your brush.) In the painting of the face there were times when I could detect the slightest bit of bleeding—very, very slight. Definitely not enough to deter me from using this pen on this paper. Now I have to test other papers I typically use. I used Daniel Smith Watercolors, transparent pigments, so that any bleeding would be visible.
I haven't had a chance to do much sketching with it since I picked it up because of other duties. But I am enjoying it. It is a little more rough and stiff in feel than some of my other favorite pens, but I am looking forward to using it on a bunch of different papers—so my mind is still not made up.
I can't tell you if the ink is lightfast or not. I can however tell you that when I tested the ink on Arches Text Wove which causes all inks to float a little bit for a little while, I could watercolor over the pen lines, almost immediately, with only a very slight bit of bleeding (that some folks wouldn't notice) or none at all (depending on how thick the lines I had laid down were). So this is definitely a pen that I will be carrying around with me to test in other situations and on other papers.
Wet Paint was going to offer their stock for sale at last weekend's comics event. I would call before you stop by to pick one up.
While I don't know how each of you draws or bears down on a pen I will offer this suggestion: If you are only going to get one I would go with the 05. I tested the 03 and found that you can press lightly to get a thinner line, and then regular strength to get a full line, and harder to get a bit of flex for an even darker line. The difference between each of those lines isn't obviously great—I'm betting that if I have the thicker nib I can easily get a thicker line of that nib's "natural inclination" and then finesse thinner lines out of it, because that's how I spend my life, trying to finesse things (or so it seems, and I'm not complaining, I'm just saying). I'm picking up an 05 that I put on hold after my first test. I wouldn't get the 01 unless you work on really smooth, plate paper.
I'll keep you posted on future tests, but I wanted you to know about this so you could look into it for yourselves.
Additional Details: A $20 price tag per size pen; cartridge packs are about $9 for 6 cartridges. The pen comes with two cartridges that can both ride in the barrel of the pen.