Dianshi 點石 Quick Dry Vintage Ink Pens with 0.5mm nib. Available in 20 different colours, you are bound to find one that would suit your writing needs. These pens are refillable but please ensure you select the right refill product.
You can also look at the DS Dual Colour Vintage Ink Pens if you’d like a colour and a black inked pen in one convenient barrel.
Actual product colour may vary from photos shown here due to lighting conditions and/or different monitor/screen displays.