Namisu Naos
One of my favorite pens. The stainless steel grip and aluminum body provide great weight balance. A nice wide grip that’s slightly textured with the machining marks. The square cut threading is inspired. The clip is an optional part that is purchased separately.
Variants: Rollerball and fountain pen in a range of colors and two body material options. Aluminum or titanium body with a stainless steel grip, cap, and clip.
Refill: Euro-type rollerball refills. Likely also fit a Pentel EnerGel but haven’t tried that hack.