top of page
Search

OHTO GS02 vs Uni-ball ZENTO Flow: Which 0.5mm Pen?

Writer: Riku Morihata
Riku Morihata
6 days ago
2 min read

Choose the OHTO GS02 if you want a fine needle-point tip and an all-metal body for neat, detailed writing. Choose the Uni-ball ZENTO Flow if you want a smooth, low-friction line in a retractable pen and a slightly lower price.

Marukaku sells both pens. This guide compares listed features; ink feel, drying and bleed depend on your paper and writing style, so it is not a measured test.

OHTO GS02 0.5mm roller gel pen

The quick comparison

  • Ink: OHTO GS02 uses ceramic roller gel ink. Uni-ball ZENTO Flow uses black ZENTO water-based ink.

  • Tip: GS02 has a 0.5mm needle-point tip with a ceramic ball. ZENTO Flow has a 0.5mm point in a retractable body.

  • Body and grip: GS02 has an all-metal body with a hexagonal grip. ZENTO Flow has an anodized aluminum grip and a movable clip.

  • Refill: GS02 takes OHTO PG-M05NP. ZENTO Flow takes Uni UBR-Z-05.

  • Colors: GS02 in Old Green or Matte Silver. ZENTO Flow in Jade or Hematite.

  • Price at Marukaku (November 2, 2026): GS02 from $13.99, varying by color. ZENTO Flow $11.90.

Ink and writing feel

Uni-ball ZENTO Flow 0.5mm pen

The GS02 uses a ceramic-ball gel system designed for smooth, steady ink delivery. Gel ink usually gives a crisp, saturated line, which suits small handwriting and annotations.

The ZENTO Flow uses Uni's black ZENTO water-based ink, which Uni designed for a low-friction feel with reduced feathering. Choose it if you want the pen to glide with very little pressure.

Test both on your own notebook. Allow the ink to dry before you highlight over it.

Tip and precision

The GS02's needle-point tip leaves the writing area easy to see, which helps with tiny lettering, margins and planner boxes. The ZENTO Flow has a 0.5mm point in a retractable body, so there is no cap to lose when you are jotting notes on the move.

Grip, body and refills

Both pens use metal where your fingers rest. The GS02 is all metal with a hexagonal grip, so it feels firm and solid. The ZENTO Flow pairs an anodized aluminum grip with a movable, color-matched clip you can position where you like.

Both are refillable. Buy the PG-M05NP refill for the GS02 and the UBR-Z-05 for the ZENTO Flow. A shared 0.5mm size does not make refills interchangeable.

Who should choose which?

  • Choose the OHTO GS02 for detailed notes, journaling and anyone who likes a fine, visible tip.

  • Choose the Uni-ball ZENTO Flow for fast, light-pressure writing and a retractable everyday pen.

  • Consider the Uni Jetstream Lite Touch ($4.99) if you want a low-cost ballpoint instead. Compare GS02 and Jetstream Lite Touch.

FAQ

Can I swap refills between the GS02 and ZENTO Flow?

No. The GS02 takes OHTO's PG-M05NP and the ZENTO Flow takes Uni's UBR-Z-05. Buy the refill made for your pen.

What refill does the OHTO GS02 use?

OHTO specifies the Ceramic Roller Gel PG-M05NP, a 0.5mm needle tip refill.

Which pen is better for journaling?

The GS02's fine needle tip suits small writing and detailed layouts. The ZENTO Flow suits longer passages where a light, smooth feel matters more.

Our recommendation

For precise, small handwriting, choose the OHTO GS02. For an easy, smooth everyday pen, choose the Uni-ball ZENTO Flow.

Comments

bottom of page