Getting discounts while using ETC on Japanese motorways

I have been driving to and from Tokyo every week for over 6 months now. There are several ways to get discounted motorway travel. All methods I have found are based on the time you enter and exit motorways. All discounts require that you have ETC fitted to your vehicle. None are easy to understand - lots of Japanese drivers have no idea how to work them!
Please do your own study and add to this thread.
What I have found is as follows:
DISCOUNT FOR MOTORWAYS BESIDE LARGE CITIES
If you leave or enter Tokyo, Nagoya or Osaka between 10.00 pm and 6.00 am you can get a 50% discount for the first/last 100 Kms travelled - if you travel more than 100 kms you will not get a discount. You have to either enter or exit a toll gate between this distance to qualify. For example when leaving or entering Tokyo you must travel through a toll gate up to 100 Kms after you leave or less than 100 Kms before you arrive in Tokyo. Lots of drivers do "U" turns at the gates to re-enter the motorway and get this discount and if you intend to do this please be careful. I think it is very dangerous but seems to be quite legal. The most discount you can hope to receive is about 1000 Yen so it is certainly worth taking the effort especially if you travel regularly.
DISCOUNT FOR MOTORWAYS AWAY FROM LARGE CITIES
If you are entering or leaving the motorway outside the major cities then you can get a discount on the first 100 Kms if you enter or leave a toll gate between 5.00 PM and 8.00 PM or 6.00 am to 9.00 am. It works the same as above, just the times are different.
DISCOUNT BASED ON EARLY MORNING DRIVING
If you drive between 12.00 Midnight and 4.00 am on most motorways you will get a 30% or 40% discount for all the time you are driving between these hours. This discount will be applied when you leave the motorway. You can enter the motorway before or during the discount period to qualify. It is calculated by time rather than distance. For maximum discount to be achieved it is better to travel as much of the journey as you can within the discount period.
Sorry I cannot make it much easier to understand these discounts! They are very complicated and even my wife, who is Japanese, couldn't understand them!
They are designed to reduce traffic during the busier times and to give cheaper travel to regular commuters.
I have saved a lot as I travel every week but even if you are only going out for a skiing trip or once in a while they are worth knowing. Every week I save about 2500 Yen on my return trip.

Thanks Asamayamaman for this very informative message.

I just have one question : for the "DISCOUNT FOR MOTORWAYS AWAY FROM LARGE CITIES", do you get this discount only if you travel 100 km or less, or do you get part of it, too, if you travel for longer distance?

Thank,

sanji

Hi Sanji,

You only get the discount for 100 Kms or less. For example if you have to travel for 150 Kms you will need to leave the motorway less than 100 Kms after you start and then go back on for the final part of the journey. It is a pain to do this but you will save money as long as you do so within the times set. I don't think that the discount applies to every motorway so you will have to check...I checked this out but just doing it. When I first started I didn't always get a discount because I didn't understand the time restrictions.
If you travel between midnight and 04.00am you will automatically get the discount no matter how far you travel as it is time linked and not worked out by distance.

Thanks Asamayamaman for those details. I will try to find the list of IC from where that discount apply...

sanji