Fountain Pens
Pilot Kakuno review
Built for children, which is exactly why it works for adults learning the same things they were: how to hold it, and which way is up.
How this page is funded. Buying through a link here earns us a commission at no extra cost to you. It does not change what we recommend or the order we recommend it in, and we have not hands-on tested these products — see how we choose and the full disclosure.
The Kakuno was designed for Japanese schoolchildren, and every decision in it follows from that brief. The barrel is hexagonal so it does not roll off a desk. There is a face embossed on the nib so you can tell at a glance whether you are holding it the right way up. The nib is tuned to be forgiving rather than fast. And Pilot publishes the line width — 0.3 mm on the Fine — because a school buyer wants to know.
It shares a nib family with much more expensive pens
The steel nib here is from the same family as the one in the Pilot Metropolitan, which costs several times as much. What the Metropolitan adds is a brass body and a sense of occasion; what it does not add is a better writing experience.
If your priority is the line on the page rather than the object in your hand, the Kakuno is the better value of the two by a wide margin.
The cap does not post
This is the real limitation and it is worth knowing before ordering. The cap will not fit on the back of the barrel, so you either write with a slightly short pen or find somewhere to put the cap. For large hands that is a genuine annoyance; for small hands it is not an issue at all.
Quick picks
Ranked for the beginner buying their first setup. Every pick names who it is wrong for.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | No image Pilot Kakuno A hexagonal barrel that will not roll off a desk, a smiling face on the nib to show which way is up, and a genuinely good Pilot nib underneath. | Younger writers and small handwriting | Check price on Amazon #ad No live price right now. How this is funded |
| 2 | No image Pilot CON-40 converter The screw converter that fits the widest range of Pilot pens, including the ones with narrow barrels. | Bottled ink in a Metropolitan or Kakuno | Check price on Amazon #ad No live price right now. How this is funded |
| 3 | No image Pilot IC-100 cartridges, blue-black Pilot's own cartridge, sold twelve to a box, and the only cartridge that fits a Pilot fountain pen. | Refilling a Metropolitan, Kakuno or Prera | Check price on Amazon #ad No live price right now. How this is funded |
1. Younger writers and small handwriting
Pilot Kakuno
A hexagonal barrel that will not roll off a desk, a smiling face on the nib to show which way is up, and a genuinely good Pilot nib underneath.
#ad No live price right now. How this is funded
The Kakuno was designed for Japanese schoolchildren, and every design decision follows from that: hexagonal so it stays put, a face embossed on the nib so you can see at a glance whether you are holding it upside down, and a nib tuned to be forgiving rather than fast.
It shares a nib family with the Metropolitan, so the writing experience is closer to that pen than the price gap suggests. What you give up is the brass body and the sense of occasion.
The cap does not post, which is a real annoyance for anyone with large hands — you either hold a slightly short pen or find somewhere to put the cap.
| Line width | 0.3 mm on the Fine nibStated in the listing's own product attributes.Source: Pilot Kakuno, Fine (retail listing, read 2026-09-01) |
|---|---|
| Nib grades offered | Extra Fine, Fine, MediumSource: Pilot Kakuno, Extra Fine 0.3 mm (retail listing, read 2026-09-01) |
| Body | Hexagonal plastic barrel; the cap does not postSource: Pilot Kakuno, Fine (retail listing, read 2026-09-01) |
| Filling | Pilot proprietary cartridge, or a Pilot CON-40 converterSource: Pilot CON-40 converter (retail listing, read 2026-09-01) |
What it does well
- The maker publishes a millimeter figure for the nib
- Hexagonal barrel does not roll
- Same Pilot nib quality as pens costing twice as much
What it does not
- The cap does not post on the barrel
- Unmistakably a children's pen to look at
- Proprietary Pilot cartridges
Skip this if the pen has to look serious on a desk at work, or if you have large hands and need to post the cap.
2. Bottled ink in a Metropolitan or Kakuno
Pilot CON-40 converter
The screw converter that fits the widest range of Pilot pens, including the ones with narrow barrels.
#ad No live price right now. How this is funded
Pilot sells several converters and they are not interchangeable. The CON-40 is the small one that fits nearly everything; the CON-70 holds far more but only fits wider pens.
The CON-40 has agitator balls inside it, which look like a defect and are not — they stop ink clinging to the walls.
If you own a Metropolitan and want to use a bottle, this is the part.
| Type | Screw-type converterSource: Pilot CON-40 converter (retail listing, read 2026-09-01) |
|---|---|
| Fits | Pilot fountain pens that take the CON-40, including the Metropolitan and KakunoSource: Pilot CON-40 converter (retail listing, read 2026-09-01) |
| Capacity | Not published |
| Larger alternative | The CON-70, for pens with a wider barrelSource: Pilot CON-70 converter (retail listing, read 2026-09-01) |
What it does well
- Fits the widest range of Pilot pens
- Cheap enough to buy two
- Screw fitting will not fall out
What it does not
- Small capacity
- Not interchangeable with the CON-70
- Pilot does not publish the capacity
Skip this if your Pilot takes the larger CON-70 — buy that instead and get double the ink.
3. Refilling a Metropolitan, Kakuno or Prera
Pilot IC-100 cartridges, blue-black
Pilot's own cartridge, sold twelve to a box, and the only cartridge that fits a Pilot fountain pen.
#ad No live price right now. How this is funded
Pilot, like LAMY, uses its own cartridge size. If you own a Metropolitan, a Kakuno or a Prera, this is the refill, and an international standard cartridge will not go in.
Blue-black is the useful default: dark enough to read as serious, distinct enough from black to be legible in the margin of a printed page.
Twelve cartridges is roughly a year of light use.
| Format | 12 cartridges per packSource: Pilot Namiki IC100, blue/black (retail listing, read 2026-09-01) |
|---|---|
| Fits | Pilot fountain pens that take the IC-100 cartridgeSource: Pilot Namiki IC100, blue/black (retail listing, read 2026-09-01) |
| Also available | Black and blue, same pack sizeSource: Pilot Namiki IC100, black (retail listing, read 2026-09-01) |
| Published drying time | Not published |
What it does well
- Twelve per box, so it is a long time between orders
- Blue-black is a genuinely practical everyday color
- No mess and nothing to clean
What it does not
- Proprietary to Pilot
- Expensive per milliliter next to bottled ink
- Only three colors in common US circulation
Skip this if you have a CON-40 or CON-70 converter — a bottle costs far less per fill.
Buying one for a child
Two adjustments. First, use cartridges rather than a converter — less to spill and less to explain. Second, choose the Fine rather than the Extra Fine: a slightly wider line is more forgiving of a hand that has not settled yet.
The paper still matters. School exercise-book paper is thin, and a fountain pen on it will show through. A cheap Japanese notebook costs very little and removes the problem.
Who should buy something else
Anyone who needs the pen to look serious. The Kakuno is unmistakably a children's pen — bright plastic, a smiling nib — and no amount of good writing changes how it reads on a meeting-room table. The Metropolitan is the same nib in a grown-up body.
Questions people actually ask
Is the Pilot Kakuno a good first fountain pen?
Yes, particularly for a younger writer or anyone with small hands. The published 0.3 mm Fine nib is narrow enough to behave on thin paper, and the hexagonal barrel keeps it on the desk. Its main drawback is that the cap does not post.
What is the Kakuno's nib width?
0.3 mm on the Fine, as stated in the product listing. Pilot also sells Extra Fine and Medium versions of the same pen.
Does the Pilot Kakuno take a converter?
Yes, the Pilot CON-40. It uses Pilot's proprietary cartridge otherwise, so international standard cartridges will not fit.
Is the Kakuno the same nib as the Metropolitan?
It is from the same Pilot steel nib family, which is why the two write far more alike than their prices suggest. The Metropolitan's advantage is its brass body, not its nib.