Pens and Pencils | Reviews and Data

Uni-ball One and One F Gel Pen

The Uni-ball One is a gel pen that uses pigmented ink in order to produce clearly writing and water-resistance.

The pen was announced on January 21, 2020 and released on February 26, 2020. That’s a quick turnaround time for a pen from a Japanese manufacturer but it doesn’t decrease from the excitement of this new gel pen.

The pen has a minimalist design, but its main selling point is a pigmented ink which will be sold with a set of new refills, call the “UMR” family. The UMR refills are generally seen in Uni’s Signo pens, but to date they have been non-pigmented inks. The pigmented inks have darker colors and water-resistance that normal gel inks can’t match.

The other cool feature of the One is the open wire clip. It’s essentially a spring-loaded clip like that found on the Sarasa Dry pen, but with a sturdy piece of wire as opposed to a plastic body. The One was initially be sold only in 0.38 mm (model UMN-S-38) and 0.5 mm sizes (model UMN-S-05), in 20 and 10 color options respectively. The retail price of the Uni-ball One is 120 yen.

The pigmented ink isn’t just useful for water-resistance and use around paint. Uni asserts that darker colors are easier to read and create writing that is more memorable than lighter colors.

Uni-Ball One F

Uni-Ball One F

On September 21, 2021 Uni-Ball released the One F, which is essentially an upgrade to the original One pen. The new model has the same basic design but it can be differentiated from the original by the metal tip protector and new body colors, like a pink, neon green, and light blue.

The One F has an improved pigmented ink with a darker black tone and more vibrant colors on the other inks.

As of November 2021 the pens were starting to become available through specialty retailers but were still generally hard to find. They are sold in 0.38 mm and 0.5 mm sizes, like the original, in all the normal colors but none of the limited editions. The One F pens typically sell for $1 more than the original.

Limited Editions

Throughout 2021 a number of special edition Uni-ball One (not One-F) packs were released. These were 4-color sets with a theme around which the colors in the pack were picked. They included:

  • Fruit Tea Color: Relax, Refresh, etc
  • Spring Color
  • Summer Color

The naming was hard to understand at the time, but one example was the Fruit Tea Color series, which contained the Relax color set. This Relax set had four pens, the colors of which were pea, lemon, fig, and black.

Uni-ball One and One F Gel Pen Information

Street Price Check Price
Manufacturer Uni
Pen Type Rollerball / Gel
Barrel Color White, Black
Barrel Material Plastic
Grip Color White, Black
Grip Material Plastic
Country of Origin Japan
MSRP $1.50
Still Sold Yes
Release Year2020
Similar To
Capped? Retractable?Retractable - Top Button
Weight (g)
Ink Color ShippedBlack, red, blue, yellow, orange, green, pink, sky blue, light pink, blue black, royal blue, light blue, mandarin orange, lime green, emerald, baby pink, violet, brown black, bordeaux black, green black