The Pilot Iroshizuku line has a certain flex to it, I think. Especially good for writing things that need to look like they have some flex.

So I bought a printer with cheap consumables, but even this thing still squeezes you for every last drop where it can. Meaning… No ink in the box. You just get one test cartridge. Good thing the ink really is cheap — dirt cheap on Taobao or JD.