Kansai Airport...but it was ~12 years ago, before the airport existed...nuthin' but cabbage & onions as I tell my divers from Japan.) Anyhow, I taught English for a small school there.
Regarding prices, I haven't lived in Japan in a while, as I said....the "name" hotels tend to be pretty expensive. In Guam it definitely pays to be (as to "pass" as) a local. The Nikko Hotel, for example, has a really good lunch buffet...$9.90 for locals, and about $16 for tourists. Even cheaper (but not as good) are the food courts in the major shopping places (Micronesia Mall, Guam Premier Outlet) where you can usually get meals for around $5 or $6. Or buy ramen at the grocery store (Payless) for .25 a pack & boil some water!
I think you said you were taking OW from MDA? I don't know if they have a different "local" vs "tourist" price. Probably too late to do anything about it if you already signed up. I'm pretty sure I saw a "$99 OW course" sign out in front of their shop...not sure if gear rental, course materials, etc are covered in that price. I know the going rate for the tourist-oriented shops is somewhere around $350~400 for an OW course...and that probably doesn't include the books. Most places don't charge OW students for gear rental...(AOW have to pay)...BUT they may require you to have/purchase your own mask, fins, boots, snorkel for the class.
Some people mentioned that 3~4 days isn't enough time...well, it takes a long time to become a "good" diver...but you can learn enough in a few days so that you should be able to continue to practice & become reasonably competent on your own. There are actually shops which do a 2 day course....academics for about 1/2 the day, then hit the beach in the afternoon & the following day. I don't recommend them...especially when (as happens here) you get tourists showing up with NO prior preparation (such as having the book, etc.) I'm not sure where you two are from, but I think Americans, in general, after their OW course and a few "guided" dives expect to be able to dive without a guide under normal conditions....but many Japanese, regardless of experience, are accustomed to ALWAYS having a guide/DM along with them, which results in less than adequate skills in many cases. Fine with me, though...if they didn't want a guide, I wouldn't have many customers!
Sorry this is long...I have Jen's (or at least someone CLAIMING to be Jen, you never know these days!) email, so I'll just reply directly to any questions you might have. My partner is Japanese, so if you have any Japanese friends with questions, I can pass them along to her. (I speak Japanese, but don't read kanji much at all.)
See you later,
Chris