Does Japan lowering the age of an adult from 20 to 18 do little to effect real reasons the nation's birth rate is in decline?

Japan has been trying to increase political education and responsibility among its younger citizens.
Recent signs looks promising.
In Dec '14, just over 32% voted in the Lower House election.
This year 60% say they plan to vote in the Upper House election.

Birth rates tend to decline when a country becomes more industrialized.

The two aren't related... It would be an over-simplification if one were to suggest a link,it isn't logical.