Before adjusting for inflation, their GDP is at 1994 levels in USD terms. If you adjust for inflation, it's a brutal rollback.

Not only did they stagnate on economic output, they accumulated extreme amounts of debt, heavily debased the Yen, saw their savings rate drop to near zero, and lost their demographics age wise.

They have to perpetually destroy their economy via currency debasement until the national debt is effectively defaulted on to a high enough degree that they regain economic breathing room. The net result of that is vast wealth lost, and a gradual adjustment down in relative terms for their economic standing vs other nations (they've fallen from a top five GDP per capita nation, to number ~20; most likely that down trend will continue at least until they're between Spain and Taiwan in rank).