It is simple.
Only "CEP" can be purchased at a partnering car rental company.
As there are limited numbers of ETC cards, reservation is necessary only in advance.
(All cars are wearing card slot of ETC no worry)
CEP discounted service offered by expressway company "Central Nippon Expressway",
so you can not book at car rent company's web,
but you can order additional anytime after you arrive in Japan. (but pls contact them ASAP.)
The vallidity roads are shown on that map as Orange line,
but car rent fee, fuel cost and drop-off fee are belonging car rent company,
so it is not included in CEP, also parking fee no related.
In Google MAP all the toll roads are written in same fat Orange color using,
but roads without ETC gates are also included, so pls compare with PDF carefully.
(most gate "street view" works, very easy to confirm)
"ETC system" is just yr car can thru at the tollgate without getting paper tickeat and payment,
so no extra payment if passed over hundreds times in and out while valid periods of CEP.
http://global.c-nexco.co.jp/en/etc/https://rent.toyota.co.jp/eng/service/option.html#anc_etcIf still wondering, you can also send the same question directly to Central Nippon Expressway.
https://highwaypost.c-nexco.co.jp/sys/inquiry/en-entry/agree/(small tips)
Although you do not have to remove the card every time,
if you start the engine without inserting it, a message "Pls, insert a card!" out,
then after reading the card, "confirm it." and card's expiration date announced.
https://youtu.be/_OsW_KvaU-chttps://youtu.be/RY7wUG6Irxs(In some models can switch to English or simple sound only, but not so many.)
Car navigation(Japanese calling "car-navi" only) system can be operated in English, no worry.
(Navigating message also in English)
https://youtu.be/VxE_PS-54JsUsing ETC is only in Japan, so do not just assume the use of foreign drivers.
ETC will not speak frequently like a car navigation system.
However, pls be careful ETC doesn't to tell you about insert the card forgetting before tollgates,
only when start and stop the engine. (except type of car navigation including)
https://youtu.be/e8iItsgkEZsETC machine position is different depends on car,
on dashboard type requires attention to gettiing heat in summer.
http://www.jaf.or.jp/eco-safety/safety/usertest/temperature/detail2.ht...(It is not easy to break, but)
ETC slot body can not be removed.
Finally, do not forget learn about traffic rules and more basics.
http://www.hkd.mlit.go.jp/topics/toukei/chousa/h20keikaku/e/e_all.pdf