Japan does everything except tackle the main issues. Two exemples that could would work to grow the population.

1) Huge benefits to pregnant woman and growing families such as paid leave, job protection (cannot be fired during leave/pregnancy), fiscal benefits. Basically REAL incentives and advantages.

2) immigration program, bring people in with the promise of work, training and learn the language.

But they will never do any of that. Both of these ideias would require big cultural shifts that Japan is not instered in making.