Yes, any time you inject a huge sum of money into the economy there will be a boost to that economy. Japan will benefit from this economic stimulus, certainly in the short term. Hopefully there will be enough new business generated that the stimulus will have long-term positive effects as well.
Usually, measures by governments prove to be effective in improving economic outcomes like spending, earning, and workforce participation. Stimulus packages are designed by economists and politicians to affect the day-to-day lives of a country's citizens in measured, positive ways. Japan's economy should be no different and the economic stimulus package should be effecting in boosting the economy.
The new economic systimulous plan is designed to boost jobs and to ensure that people have more money to spend. By following sound financial advice when creating this stimulus plan, Japan is ensuring that they will have a healthy economy and happy, satisfied people for many years to come in the future.
Japan's economy has not been growing robustly for at least two decades now. I doubt whether a stimulus package will help kick start the economy as I feel that there may be institutional problems within the economy that need to be addressed first. The Japapnese often work their employees too much which makes me think there may be a feeling of resentment among the population which is stopping the economy from booming.