And going by the flag you've selected, the ink ought to be readily available in Japan.
The answer will depend not only on the ink, but also the paper and the pen. If you write on sketchbooks made of newsprint, that will reduce dry times and increase feathering. If you use 62gsm Tomoe River paper, that will reduce feathering, but increase dry times.
I'm going to repeat three suggestions that I see made a lot, basing them on the assumption that you'll often find yourself writing in "blue books" made of paper not much (if any) better than newsprint pulp. I have no experience of the inks I am discussing; merely the collected tales of those who do.
First, get a Japanese pen. A Japanese medium writes about like a Lamy XF, and if you're writing in Japanese characters, you'll want the finer lines. And the less ink your pen lays down, the faster that ink will dry.
The first ink I'd suggest is a Sailor nano-pigment ink, e.g. Sei-Boku (blue-black) or Kiwa-Guro (black). These inks are highly regarded for their ability to keep tight lines without feathering, even on bad paper. You don't want to let these dry out in your pen, because while the nano-particles may be small enough that the brownian motion of the water molecules will keep them in suspension, there is no guarantee that they will go back into suspension should the water all evaporate.
The second thing I'd suggest is an iron-gall ink. They are a transparent solution of ferrogallic acid that oxidizes into an insoluble dark-grey solid, with various dyes and colorants (blue is the classic colorant) so you can see what you've written while waiting for the precipitate to form. The reaction starts within seconds, but it may take hours or days for it to completely finish. Like the nano-pigment inks, iron-gall inks strongly resist feathering, but again, it's a bad idea to let them dry out in the pen, because the acid will turn into the solid precipitate, and you'll need to clean it out with a suitable acid. There's a thread around here somewhere on cleaning up this kind of mess, but I'm not going to look it up just now. One member has kept a Pilot Plumix filled with IG ink for years, without flushing, and had no troubles.
Platinum's new "Classic" line is a series of iron-gall inks that ought to be available to you locally. So too might Pelikan 4001 Blue-Black. And Rohrer & Klingner make a couple of iron-gall inks, Salix (blue-black) and Scabiosa (purplish-mauve).
Finally, because you won't want to let these inks dry out, I'm going to suggest a Platinum Plaisir. It's relatively inexpensive, and I doubt there is a better pen at the price point for not drying out.