People visiting Japan should obtain a visa from any Japanese diplomatic mission unless they are from visa-exempt countries. If you're going for a same-day transit between international flights at the same airport, you need no visa, but you cannot leave the area. But once you enter Japan, you must keep your passport with you always.
For Indian citizens, an application can be made at any of the embassies in India - New Delhi, Mumbai and Kolkata. Fill in the application form and submit it at the application centre. Processing usually takes between 5-6 days.
Visa for Indians - Fee & Requirements
Filled out application form
Copy of the passport
Relevant financial documents
Copy of your return flight ticket
Countries that do not need a Visa for Japan
EU & EEA member states, Andorra, Australia, Argentina, Bahamas, Brunei, Canada, Chile, Costa Rica, Dominican Republic, El Salvador, Guatemala, Honduras, Hong Kong, Israel, Macau, Macedonia, Mauritius, Mexico, Monaco, New Zealand, San Marino, Singapore, South Korea, Suriname, Switzerland, Tunisia, United States/American Samoa, and Uruguay