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Pen Review: Is the Uni Zento Gel Pen Worth the Hype?

August 16, 2025

One of the most-discussed releases of the past year has been the Uni Zento gel pen, which has captured the attention of the stationery communities in both Japan and the U.S. In particular, the “Zento Signature” - which features a cap as opposed to your typical retractable mechanism - prompted rushes reminiscent of the Uni Kuru Toga Dive mechanical pencil. While I’ve yet to get my hands on one of these “upscale” models for an extended test drive, I’ve had the opportunity to write with both the standard Zento and the slightly upgraded “Zento Flow” (both retractables) for a couple of weeks now. While I’m not sure I would pay more than standard retail for any version of this pen, the Zento is an excellent gel pen and so far I prefer it over the Uni One and any of the basic Uni Signo “office” inks.

The Uni Zento Flow Gel Pen in the Jade Colorway, in-hand. I also went with a Canary Yellow standard Zento.

So What’s the Story Behind the Zento?

Uni’s gel pen lineup can be confusing - the company has released multiple iterations of your standard black/blue/red gel pen and left them all on the market simultaneously, the only difference supposedly being different inks that to most people will seem quite similar. The Zento is advertised as formulated for “stress free” writing, which apparently refers to a combination of smoothness and cushion. The Zento is indeed quite comfortable to write with - the pen feels very smooth with little to no scratch, and the ink glides on the page and dries instantaneously. The ink is also advertised as formulated to reduce feathering and bleedthrough, and I can confirm there is none. Now was this actually so much of an issue with Uni’s other pens that it warranted an entirely new product line? I’m not sure, but it doesn’t change the fact that the Zento is good.

Ink Comparison: Zento Black Ink (top) has a more matte look, vs. the glossy black Uni One (bottom). To draw a comparison to fountain pen inks, I’d compare the Zento ink to something like Platinum Carbon Black or Sailor Kiwa-Guro, while the Uni One ink is more of a glossy black like Aurora.

How Does the Uni Zento Compare to the Uni One?

As I noted, in addition to the Zento, Uni released the Uni One a few years ago, which was supposed to be another “specialty” ink that’s a step above your standard office gel pen. I’ve found the Uni One and the Zento to offer somewhat different writing experiences, so I can confirm the distinction is real. The One contains an ink formulated to be extremely dark (standard black) and/or vivid (other colors), with a glossier finish. So if you prefer a darker, wet look to your gel ink, you might prefer the Uni One, especially if you’re using the pen for drawing or doing layout work in a bullet journal or planner. The Zento seems better suited to pure writing, as it lays down a remarkably smooth line and, in my opinion, has the more comfortable barrel.

The array of barrel colors available for the Uni Zento standard. There are some great colors available.

Takeaways and Where to Buy

Uni makes a great gel pen, and I surprised myself with how much I enjoyed the Zento as I don’t typically do much writing with gel ink beyond quick notes and annotations. I strongly prefer the barrel on the Zento over the One and pretty much any other standard gel pen - it’s got a nice balance, the perfect diameter for my hand, and on the standard model, a soft texture that’s comfortable over longer sessions. I will also say that the clips on both the Uni Zento and the Uni One are excellent - the wire design is highly functional - with the slight edge to the Zento as it feels a bit tighter on both the standard model and the Flow. That said, if you prefer the barrel on the One but want to try Zento ink, the Zento refills fit the Uni One, and vice-versa.

We currently have a large selection of the standard Uni Zento gel pens available in our shop, as well as a smaller selection of the Zento Flow, with the upgraded barrels. Zentos are priced at $3 and $11, respectively, with extra refills available for $1.75. You can get a nice pen at a reasonable price, or pick up a refill that will fit one of your existing Uni pen bodies.

Come see these pens in person! Visit our shop, currently open Thursday and Friday 1-6pm, and Saturdays 10-6pm. Check this page to keep up to date on our current hours, which may change depending on travel schedules during pen show season.

You can tell the difference between the clip on a Zento (top and bottom) because it has the round holder, whereas the holder on the One is rectangular.

In Pens Tags Uni Zento, Gel Pens, Uni, Uni Zento Flow, Pen Review
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