uniball ZENTO 3-Color Ballpoint Pen / uni Mitsubishi Pencil

• Ink Colors: Black, Red, Blue
• Ink Type: Water-based ballpoint
• Tip Sizes: 0.38mm, 0.5mm
• Body Colors (0.38mm): Linen, Mist, Canary
• Body Colors (0.5mm): Slate Gray, Lavender, Adobe
• Grip: Wide rubber grip
• Knock Style: Retractable knock button

The ZENTO was developed around a single engineering goal: remove the friction that makes water-based ballpoints feel scratchy or inconsistent. The ink uses a POA surfactant (polyoxyalkylene) as a cushion component, reducing friction resistance during writing by approximately 40% compared to conventional uni water-based ballpoint formulas. A second ingredient, attraction particles, pulls ink back slightly after each stroke to suppress spreading, bleeding, and bleed-through.

The physical design follows the same logic. The barrel is shorter than a standard ballpoint so fingers naturally settle near the knock button without any repositioning. The knock mechanism itself was tuned to minimize the bump sensation on each click. Color identification was also considered: the body colors are deliberately muted and the ink window is positioned to reduce visual clutter, so you can tell black, red, and blue apart at a glance without rotating the pen. The wide rubber grip covers the full contact zone where fingers and the side of the hand rest during extended writing.