Unlikely, though this would depend on your definition of "cities/urban areas". In written sources we have three points of data:

1. The Book of Wei put Tsushima at 1,000 households in the late third century, which would be about 4~6,000 people.
2. In the Edo period the island's population fluctuated between 20,000 and 32,000, with between a third and half of that in the clan's capital. This is after significant population boom and increase in trade activity in the late Sengoku and early Edo.
3. The Hachimangudōkun says the lord of Tsushima engaged the Mongols with ~80 horse, which included reinforcements from Higo of unknown number (a name is mentioned).

The Book of Wei says there's no good farm and the population lived on fishing, so they were probably spread out across coastal villages. By William Farris' numbers the pre-Sengoku Japan could support about 1.8% of the population being soldiers at maximum. If we assume each horse had a follower on foot, (it's an average between 12, I'm taking 1 to account for the fact that some of them wouldn't be from Tsushima), that makes maybe 160 soldiers from Tsushima which would put the population at about 9,000. Even if we assume half of that lived at the Tsushima provincial capital (and I highly doubt it was that high), the capital would still be below 5,000 people, the cut-off that Faris use for the population of a town. The capital being a town of 5,000 is a possibility, though I don't expect it to have had any more than 24,000 people.

On the other hand the "horse" counter ki is often used to mean all soldiers, which would make the island's population below 5,000. This would mean any population center could have been smaller than Neolithic Jericho.

Note today Tsushima's population is only 30,000. While there has been significant decrease due to aging population and urbanization, the island's population didn't break 70,000 at maximum in the 1960s.