Japan is a dream destination for many & so its for me.
Once you visit Japan, it is going to remain in your mind for quite long.
The cheapest month to fly to Japan is October. you can book return ticket as low as 25k however i booked it in 35k Delhi to Narita Airport (as i booked a month in advance).
I booked my flight through ANA (All Nippon Airlines) & flight time was approx 8 hours. My flight started 1am in night from Indira Gandhi Airport and landed in Narita airport at 12:30 PM
Oh yeah. Japan visa is quite cheap around INR 500 and you have to visit VFS and apply the visa for single/multi entry.
My experience in ANA was superb, i loved their hospitality and food.