As a U.S. citizenship holder, you do not need to apply for a France Schengen Visa! You are allowed to travel to France and to all other members of the Schengen Area for up to 90 days for tourist or business purposes without a visa, as long as your U.S. passport is valid for at least 3 months after your planned return to the United States!
You must have a valid passport and an onward/return ticket for tourist/business "visa free" stays of up to 90 days. Your passports must be valid for the entire time you are staying in Japan. U.S. citizens cannot work on a 90-day "visa free" entry. As a general rule, "visa free" entry status may not be changed to another visa status without departing and then re-entering France with the appropriate visa, such as a spouse, work, or study visa.
If you are a holder of the U.S. Permanent Residence Card (formerly Green Card) or U.S. visa and if you are a citizen of the countries from this list, you must apply for the France Schengen Visa which correlates with the purpose of your visit to France, as there are different types of visas available and specifically designed for your travel purpose.
The following countries are in the Schengen Area: Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden and Switzerland.