Based on this tweet she uses a Parker Sonnet (at least in volume 1):Ooooh, ok she uses Pilot fountain pen ink to write with.
The bottle in the first page is the same, plus it actually says ink on the real bottles.
She has good taste.
Nice. I've got the ink, maybe I'll get the pen. Surprised she isn't using a Japanese pen, at least on the cover.Based on this tweet she uses a Parker Sonnet (at least in volume 1):