Do I need English GPS driving in Izu?

I will be driving one day in Izu, my car rental only have japanese GPS, is it sufficient?
I do have internet data for google map but not sure the coverage in Izu...

How can I key in attraction tel number?
For example, Irozaki coast, where can I find the tel number?

TIA!

I will be driving one day in Izu, my car rental only have japanese GPS, is it sufficient?

Certainly! It is perfectly possible to drive the entirety of Japan without GPS, at all. Paper maps work, as well. And the Izu Peninsula is relatively easily navigated because there are only a relatively small number of major roads.

I do have internet data for google map but not sure the coverage in Izu...

You can expect the entire peninsula to have cell phone coverage, especially in the towns where the major intersections are located.

How can I key in attraction tel number?

Depends on the GPS system. First you have to find the button for entering the destination (usually 目的). It can be on the top page or it can be under メニュー (menu). Then, it will usually show either an icon of a phone or say 電話番号 or the like. Then, you enter the phone number.

For example, Irozaki coast, where can I find the tel number?

I find it much easier to enter such places using the map. Zoom into the location (it is the southernmost tip of the peninsula) and then click the button to select it as the destination. Which button to press can be slightly challenging, though. If you need phone numbers, it can be challenging in case of places like this. You have to try finding something nearby. But be careful that the phone number given is actually for a phone in that location, rather than the phone number in a central office somewhere else.

Alternatively, you could also try using mapcodes.

When my parents came and drove around Shikoku by themselves, I recommended they use their hotel's wifi to look up the telephone numbers on google maps the night before, then just key in all the places they wanted to go (or keep it written down). That worked well for them, because they could use google maps in English easily, and then just grab the phone numbers. So that might be another good option for you!

And if you go that route, just a quick note on phone numbers... sometimes the way the numbers are split is different, but it should always be 10 numbers. Also some guidebooks leave off the first 0 or the first few numbers, but all numbers (as far as I know) start with 0. For example, 0274-22-4455 or sometimes 027-422-4455 are the same. Sometimes google maps leaves that off, so just know its there!

Hope that helps and you enjoy your trip!

I used a rental car in izu a year ago, if you don't know your way around, a GPS is a must, japanese or english, they work the same, I used Mapcode, they seem more accurate than telephone number.