They were also much loved by scoreboard makers, who could flog off their extra-wide models whenever the Cherry Blossoms were coming to town. Famously, they conceded 145 points to New Zealand at the 1995 World Cup. Even Matt Williams, Scotland's least-lamented coach ever, managed a 100-pointer against them.
That was at Perth's McDiarmid Park in 2004. Granted, Japan had pitched up with a team that had been trawled from the second XVs of various clubs and universities and which offered all the resistance of a piece of soggy rice paper, but the fact the 100-8 final scoreline raised no eyebrows whatsoever spoke volumes for Japan's standing.
Now, however, they are no longer the whipping boys of Test rugby. They have actually delivered more three-figure thumpings than they have suffered (granted, victims have included Kazakhstan, the Philippines and the United Arab Emirates) but there is no question their stock has risen.
A rather large asterisk has to be placed against their summer victory over Wales. Most of the top Welsh players were with the Lions at the time, but they still brought a host of established names. That 23-8 win had echoes of Japan's 28-24 triumph over Scotland in Tokyo in 1989, the Scots being without their Lions of that year. But the combination of increasing domestic competition, serious international coaching talent, and renewed vigour - and money - in the game ahead of Japan's hosting the 2019 World Cup means they are now focused on their elite performers as never before.
In the past, Japan's international efforts have sometimes played second fiddle to club and, particularly, university rugby. That emphasis has changed, and while Japan will not become a superpower overnight by taking the Test dimension more seriously, it certainly brings them more in line with the rest of the planet's rugby thinking.
Yesterday's 54-6 loss to the All Blacks in Tokyo may not look too clever on paper, but there are plenty of other countries - think Scotland last year - who are just as capable of shipping a half-century against the world champions. Japan put up a decent old fight and probably finished the stronger side. They were particularly unlucky not to claim a try in the final minute when winger Kenki Fukuoka was barged into touch in the act of diving over the line.
He is one of a group of young players coach Eddie Jones - who will miss the European tour after suffering a stroke - brought into the side. Former coach John Kirwan was notorious for plugging gaps in the side with imported talent but while there are a few residence-qualified New Zealanders still in there, they now support the home-bred contingent rather than the other way round.
One to watch? Try Ayumu Goromaru, a full-back who has been compared to Gavin Hastings in his pomp.
Scotland can go into Saturday's game with confidence, but with a decent measure of caution as well.