The nib that defines manga production.
There are three Japanese G-nib makers: Tachikawa, Nikko, and Zebra. Every working manga and comic artist in Japan has a preference between them. Tachikawa's version is slightly stiffer than Zebra's, which suits illustrators who ink with a heavier hand or work quickly across large areas. The snap-back — the speed at which the nib returns to its resting width after pressure — is crisper than either alternative.
The G in G-nib refers to the shape: a broad, rounded nib body that holds a relatively large reservoir of ink before reloading is necessary. This makes it the most practical nib for sustained production work rather than short sessions.