I'm sort of not clearly understanding everything you're saying.
Looking at your linked page, I will say that their options are rather atypical. A typical situation is that the rental car agency offers one standard insurance coverage terms, with different waiver and road service options (CDW, NOC waiver, roadside service, comprehensive CDW + NOC waiver which may include roadside service and often may also exempt you from responsibility for tire damage). With your agency, what they're offering are two different types of coverage with roadside service and tire repair rolled into the superior coverage plan. Your website does not state how much the superior plan (Recommended course) costs, so you'll have to find that out. Otherwise all the info is there, and I think the wiki gives you most things you need to consider to make the decision. Only you can judge your own comfort level with different risks and how much you value things like roadside service, benefit of CDW by letting the rental car place deal with the damage versus dealing with your credit card company in case of damage to vehicle (Jpn rental car companies are sticklers for having police report for everything, but going through your credit card company will probably necessitate multiple phone calls and paperwork and lining up documentations), etc. As far as roadside service is considered, you'll be entitled to JAF service anyways if you're AAA/CAA member although I only know that on paper and don't know how seamless that is firsthand. One other variable is your credit card... significant difference between what you get from Chase United Club / Sapphire Reserve versus something like AMEx Platinum.

I agree. That type of car will also probably be really small. If I'm going to be driving around on expressways and over mountains, I'll want to at least get something like Honda Fit which is small but comfortable and has enough cargo space and oomph.

Isn't 600cc almost a moped size engine? I had a Toyota Noah minivan and it had a remarkable lack of power especially on the expressway running between Kyoto and Amanohashidate, and those were not exactly steep mountain passes.

In Jpn, I guess the smallest cars ("keijidousha") are rated as having <660cc engine cylinder volume.
Something like Suzuki Hustler (yeah funny name).
I have never rented one of those before. But I guess it'll do the job if you're just need to drive around a bit on surface streets.

I saw a Hustler parked in my lot and wanted to take a photo - obviously someone is not doing their English colloquial research before branding some of these products :)

My first couple of rentals in Japan were Prius Aqua models which did the trick for what I needed and great on gas - same as the US Prius C, except my Japanese friends pointed out that only girls and young women drove the Aqua in Japan (maybe they were making it up?), and it didn't help that Toyota Rent a Car gave me a grape bubblegum color for the first car, and candy apple red for the second one.

At least that makes it easier to find in a crowded parking lot?

Moped's in most countries is under 50cc, often as low as 35cc.

The Kei cars in Japan are more than capable of getting anywhere you want, bearing body style in mind. Some of the turbo charged Kei cars easily put out upwards of 150hp, so don't discount them.

For the week in Hokkaido in October, I am finding rentals really quite expensive. I just had a quick look at rentalcars.com to see what was on offer, generally. I still haven't got around to studying this and making a booking. I need to study this thread again, especially the post of beep88 (post #83 ). Actually, I am thinking of spending an extra night in Sapporo and cutting my rental time down to 5 days (still seems to be cheaper to rent from CTS airport). I reckon Sapporo deserves at least a day to visit it and probably a lot longer.

Arriving evening of 5th October at Sapporo CTS, departing again late morning of 12th October. I think it is not a bad idea to spend the whole day in Sapporo plus an extra night, then get on the road on the 7th, without having to worry about a car, city driving and parking (but maybe Sapporo is not that bad).

There will be 3 of us, with medium sized bags, not anything huge. We usually travel relatively light, trying to pack sensibly, given there is always the issue of lugging bags about. My bags rarely reach 20kg, and only if I am transporting music, which always makes things heavier.

Given that the car will be returned to CTS airport prior to departure, it probably makes sense to have the pickup at the same location.

FYI - Toyota Rent a Car locations "Poplar" and "Suzuran" are separate offices at CTS Information on Car Rentals To & From | New Chitose Airport Terminal. OKA also has a similar setup where rental agencies of the same corporate brand have multiple independent offices and airport shuttles.

Based on pick-up 7 Oct and return 12 Oct at CTS per Rakuten Travel, I get:

Orix Rent a Car: EA Class (eg, Fit Hybrid) 22,400yen + tax (only 2 cars remain at that price)
Times Car Rental: C-1 class (eg, Demio, Note) 31,000yen + tax
Budget: "JS" class (eg, Fit, Vitz) 22,194yen + tax
Eki Rent a Car: S class (eg, Fit, Vitz, Note) 21,920yen + tax

I think those are all reasonable prices from reputable companies.

You'll see super-low prices at other agencies, but do not go for places like Ones and NicoNico and no-name operations.
I would even hesitate to rent from places like Honda Rentacar or Honda RentaLease. Those are all local operations and I've been fine renting from them before, but their coverage and fine-print policies make me lose trust in them.

Thank you so much. I will tackle this when I get back on Monday, I am traveling all weekend. Hope I can get a booking sorted immediately. I will go through Rakuten as you said (but first I will scroll up here in the thread to remind myself what Rakuten is).

EDIT - At the cars section of Rakuten Travel, it says "brought to you by rentalcars.com"! So it is an aggregator then. I could just book it using rentalcars.com, no? It took me a while to find an English language page for Rakuten and it's a bit challenging (and annoying) trying to do it on a mobile phone. I can't even read the tiny logos of the unfamiliar rental car companies, so I will wait until I am home on Monday and do it on the computer.

I am pretty sure the quotes from #102 above are from Rakuten Japanese language site. They are certainly not rentalcars.com

Personally I would never touch rentalcars.com

Translate JP reservation sites on a computer with Google Chrome using the translate button next to the URL. You may need to switch back and forth between English/native language and Japanese to get successive drop downs to populate in English/native language. Most sites also don't like accepting the date in Translated mode so be sure to set it while in JP. You can register for a JP Rakuten account in English https://grp01.id.rakuten.co.jp/rms/n...service_id=top which will make sure the reservation is for the same Roman name as shown on an IDP- the same account works for a myriad of Rakuten JP services including JP food delivery.

Tabirai.net is also worth a look sometimes - their rates usually bundle in a CDW if you were going to opt for that & sometimes optional 24h NOC waiver is cheaper, too. It is also a JP rental car consolidator like Rakuten and Jalan. English options/available packages are more expensive than the JP options but likely cheaper than something like rentalcars.net. The English site also has CDW options in English Information regarding insurance and CDW | Tabirai Japan Car Rental