Japan's primary problem on income is that the economic ground they've lost in the last 20 years is vast. In the late 1980s, their GDP per capita was beyond that of the US. Now it needs to climb 50% to catch up. The last 20 years has taken them back to #16 among major economies in terms of GDP per capita. That gives you an idea of how difficult it's going to be for Japan to bring their incomes back in line with high per capita output economies like the US (or Australia, Denmark, Sweden, etc).
They need very substantial, sustained economic growth for a decade or more to start regaining lost ground. Their debt problems will continue to put pressure on the Yen, the debasement of which is a big culprit in the sizable drop in their standard of living over the last decade. While their interest costs are eating up such a large portion of their budget, their ability to properly invest into growth is heavily restricted. They're stuck between a rock and a hard place. I've yet to see a plan for how they're going to deal with that. To make matters worse, their savings rate has dropped to low single digits, as their standard of living has dropped they've been forced to reduce savings to try to maintain (which has further pressured the government's ability to properly fund itself, as they can no longer count on tapping into large new pools of savings via debt issuance, leading to abusing the Yen as a last resort).
They need very substantial, sustained economic growth for a decade or more to start regaining lost ground. Their debt problems will continue to put pressure on the Yen, the debasement of which is a big culprit in the sizable drop in their standard of living over the last decade. While their interest costs are eating up such a large portion of their budget, their ability to properly invest into growth is heavily restricted. They're stuck between a rock and a hard place. I've yet to see a plan for how they're going to deal with that. To make matters worse, their savings rate has dropped to low single digits, as their standard of living has dropped they've been forced to reduce savings to try to maintain (which has further pressured the government's ability to properly fund itself, as they can no longer count on tapping into large new pools of savings via debt issuance, leading to abusing the Yen as a last resort).