7 pens recommended for Hasamu A4

Hasamu A4 is an analog tool for drawing by hand and getting direct feedback from it to expand your ideas. The comfort of the pen is the key to this analog feel.
However, pen holders are limited to a 10 mm shaft diameter.
We therefore recommend the following pens that make the Hasamu A4 the ultimate analog tool.

Caran d'Ache Ecridor and 849
The immortal masterpiece of the ballpoint pen
The perfect multifunctional pen
rOtring rapid PRO 2.0
rOtring rapid PRO 2.0
Unsharpened pencils and lead holders
Cross Tech3+
Cross Tech3+
Well-balanced multifunction pen
Helvetica 3in1
Itoya Helvetica 3in1
Slim multifunction pens
rOtring 600 3in1
rOtring 600 3in1
Robust multifunction pen
無印良品 ボールペン ノック式 本体 アルミ
MUJI Ballpoint pen, nock type, aluminum body
Ballpoint pens compatible with general-purpose refills

These are listed in order of recommendation. (Discontinued products are excluded.)
Since only one pen can be attached to the
Hasamu A4, many people think that a multifunction pen would be convenient. However, most multifunction pen refills are the small and thin D1 (4C for Zebra) standard. The writing distance is only a few dozen meters with water-based gel ink to several hundred meters with oil-based ink. For example, Mitsubishi's Jetstream 0.7mm has a range of 200 m. If used on a daily basis, frequent replacement is inevitable and not cost-effective.
On the other hand, Caran d'Ache 849's Goliath lead has a writing distance of 8,000 m. Even if you write 2 m every day, the ink will not run out for more than 10 years. It is also cost-effective.

For this reason, we recommend that you use the single-function pen for daily use and limit the use of the multifunction pen to when you are out and about without carrying a pen case.