This is a set of 19 Japanese ballpoint pens.
All inks are black
0.5mm

Contents:.
Uni Uni Ball One 　　Gel Ink
Uni Jetstream 5 pens set 　　permanent ballpoint pen
Zebra Sarasa Clip　　Gel Ball Ink Water-based Pigment Water-resistant
Zebra blen 5-pens set　blen system to prevent writing vibration Emulsion ballpoint pen
Pentel EnerGel.  Gel ink
Pilot Acroball 5-piece set. permanent ballpoint pen
Pilot Frixion Ball 3 Colors　　Ballpoint pen that disappears with the heat of friction

All of them are things that I have actually used and I am introducing the ones that I was happy with.