Answer:
zero-cost infant day care and preschool centers to allow mothers to return to the workforce to make it easier to have and pay for children
Zero-cost infant day care and preschool would be a good measure in order to raise Japanese Birthrate. Many Japanese couples do not have any children simply because day care is too expensive.
Enforcing a two-child policy for all families, requiring a minimum of two children per family to become eligible to receive school services and work benefits
This measure is very authoritarian and thus, unlikely to be implemented in a democratic country like Japan.
However, if it became implemented, it could be very effective because people would be required to have at least two children in order to have access to a variety of social services.
Decreasing transportation costs to allow workers to commute from locations farther outside of densely populated urban centers
Studies have found that couples living in dense urban areas tend to have less children, probably because rent is more expensive in urban cores, and also because many people believe that urban centers are not a good enviroment for children.
For this reason, lowering transportation costs could be an incentive for families to live in less densely populated areas, where rent is lower, and the enviroment is more appropriate for raising children.