GS01 Oil-Based Ballpoint Pen 0.7mm / OHTO

• Ink Type: Low-viscosity oil-based soft ink
• Tip Size: 0.7mm
• Tip Material: Brass (needle tip)
• Barrel Material: Aluminum
• Clip Material: SK steel
• Total Length: 136.4mm
• Barrel Diameter: 9–10.1mm
• Max Width: 11.3mm
• Weight: 17.3g

The GS01 starts from a simple question: what barrel shape actually feels good to hold? OHTO's answer was to merge two geometries, a hexagonal section that gives the fingers a consistent grip plane, and a round section that eases transitions when writing angle shifts. Neither shape alone was enough; the combination is the design.

The aluminum body is finished matte rather than polished, which reduces slip without adding grip rubber. The tip is a needle-style nozzle made from brass, chosen because it places less material around the ball and lets the writer see exactly where the line is landing. This matters most for small or precise handwriting, where guessing the tip position adds up over a page.

The ink is OHTO's low-viscosity oil-based formulation, which sits between the dry feel of standard ballpoint and the wet flow of a gel. It moves with less pressure and skips less on the return stroke. The refill follows the international G2 standard, so replacement is straightforward without sourcing OHTO-specific stock.