No, plastic cartridges, but you can get a refillable cartridge.

I was worried it would be crap, because who makes a good fountain pen for $5, right? But no, it's sturdy and serviceable. You wouldn't write wedding invitations with it, but for day to day handwriting it's fine. (Daiso is a Japanese "dollar store", and everything in there is about $1.50, so $5 is high-end there, eh?)

I know what you mean about Uni-Ball's quality. I had some of the old black ones from my dad (it was his favorite pen as well) and it does feel like the new silver ones aren't quite the same, eh?

https://uniballco.com/uni-products/deluxe/

It might be something as simple and subtle as weight of the plastic.