There are quite a few models with full ovens on them, but as Gonative said - they`re for commercial use, so not what the average person would buy for use in their home. The in-laws had one, and when it broke replaced it with two separate units - a normal gas stove and a stand-alone oven that is about 3 times the size of the old (something that was like Gonative`s)
Japanese cooking doesn`t really call for a lot of baking, so for the average person installing one would be overkill and a waste of space.

Around here, at least, gas is the norm for stoves. Induction (IH) stoves are gaining market share, especially in newer homes as you can get significant energy cost discounts for being an "all electric" house.
In the countryside people tend to buy gas in tanks, and in the city it is piped in.

Personally, I prefer being able to see the flame when cooking. Induction apparently works quite well and has the same "instant" adjustment qualities as gas, but all those I have used make a terrible high pitched sound when on. I`ve encountered silent ones in restaurants, but none at the consumer level. If it makes me cringe in ear pain there is no chance of me using it on a daily basis, so we will stick to gas.

I would say almost all of them, and that it`s a combination of material, energy costs, and tradition. Older houses were really only made of the lightest materials with no thought given to insulation. They`re usually barely warmer inside than outdoors, and to heat more than a single small area would be prohibitively expensive. This is accepted and considered normal.
Therefore even in newer houses it is considered normal to not heat large areas and for it to be cold inside the house. As there isn`t an expectation of good insulation, it isn`t given much priority. You get a sort of circle cycle - as it`s normal for it to be cold indoors, people don`t expect it to not be, so it stays cold indoors making that "normal", so people don`t expect it to be anything else, so....

It is very very rare for a normal household to have anything like central heating. It is my understanding that in residential homes 75% of the central heating market caters to expats in Japan. A very very tiny percentage of the population.
In general, it`s just too expensive and considered an incredible waste. People tend to gawk at the very idea of paying to heat rooms that may not be entered all day. It`s always been tradition to gather in the warm room, so there just isn`t the same attitude toward heating / cooling as in the west. Even the general thinking regarding temperature is different - warm enough to walk around in thinner clothing is pretty much unthinkable. Warm sweaters, thick socks, a blanket, etc, are normal indoor wear during the winter.

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My "house" is a condominium/apartment, which we purchased new. We looked into purchasing a house, but wanted a living space that was as large as possible, a large garden, a parking space, and privacy. The condominium fulfilled all of these better than a house would in the city.
The average city house is around 900 square feet with a "garden" of about 50 square feet. As there is little space around the house, there is little privacy. We have 1200 square feet for living, a 200 square foot veranda, and a 750 square foot garden... Plus a private entrance area, two private outdoor storage areas(10 and 30 square foot), and a parking space. The building is designed so that there are no windows or living spaces facing another unit, so there is more privacy than the average city house.

We have yet to put any work into this place other than basic installations (built-in dish washer, shelves, etc). As far as built in heating - there is no central heating (of course), but there are gas heated floors and a bath heater / dryer. For the floors, water is heated and piped under the floor to warm the room. It keeps the room quite warm without drying the air. It`s controlled on an area-by-area basis. The bath heater / dryer is a sort of combination gas heater and dehumidifier. It has a setting to heat the bath area, or to be a powerful dehumidifier. We rarely use the heat function as running a bath and showering will make the bath quite toasty, but use the dehumidifier almost every time it rains. As clothes driers tend to be quite rare, the main options for drying clothes are hanging them outside... Or hanging them inside. We hang them outside when the weather is nice, and inside the bath with the dehumidifier running when it is humid or raining.
Clothes driers then to have incredible running costs - a friend bought a tiny one and found that it used 60 yen of energy every half-load (only half a load or less would fit in it - she`d have to run it twice to dry a single small laundry load), so it ended up being disconnected and collecting dust. To run it every day to dry a full load would have nearly doubled the bill. And it was supposedly one of the more energy efficient models!
Driers seem to be most popular and get the most use from mothers using cloth diapers. Apparently those cannot dry quickly enough, so the cost is justified.

After we moved in, we installed AC units in two of the bedrooms, and one in the living room. All of them heat, but we rarely use them for anything other than cooling. In fact, we`ve never used the living room one for heat and may never. When we do use the bedroom ones, they are on timer to come on about an hour before we wake up so that we can crawl from the bed and change clothes without freezing. The rest of the heating is taken care of by the heated floor in the living room, a kotatsu, and on occasion a kerosene stove.

I imagine the thinking toward heating is a bit different where Gonative lives - winter is longer and a lot colder up there.

AC is one thing that very few houses in Hokkaido have. The summers just usually aren't hot enough to make them worthwhile. There's usually only a week or two each summer that you may consider using one but we just use a portable fan for those periods which works fine. This last summer though, which was the hottest on record, did get quite uncomfortably warm at times!

About insulation, I'm surprised that for as "Eco" as Japan is trying to be they don't seem to put much focus on insulation. When I was looking at houses they were selling different types of insulaton from fluffy fiberglass to what was basically glorified styrofoam panels. The sellers were talking about it like it was new. The same thing goes for dual paned windows.

Upon doing some research on insulation a little over a year ago, I came across a rigid fiberglass seller nearby and got a ton for fairly cheap. I used it for sound absorption (not for my apartment). Not only does it work well for sound, but it keeps the room cooler in the summer and warmer in the winter.

Styrofoam alone aparrently reacts to sound (with reverberation and such) which is not something desirable for noise reduction. Fluffy fiberglass doesn't do much as far as low-range sound goes.

Despite the fact that I found a seller of the material, I didn't seem to find any companies who implemented it in their designs.

On a similar note, which you might find interesting (dogsbody70) is that tatami mats are actually really good sound absorbers. If anyone on here has taken all the tatami out of a tatami room (like for cleaning) you know what I mean. The room can sound like the grand canyon (all echo-ee) without the tatami in it even though it was fairly dead (in a good way) with it inside. I found out that it's particularly good for mid-low range sound but actually does reflect some higher range sounds due to its semi-hard surface (but it won't reflect like hardwood will). Not only that, but you can jump on it without having things in the immediate area rattle around. I suspect tatami is a very old form of insulation... and insulation usually means good sound absorption. In other words, I think there is a connection with some Japanese instruments (like the koto and shamisen etc) and tatami mats even if to a small degree.

The other thing I suppose that factors into the money people put into a house and things like insulation is that housing here is no longer really considered an investment. Since the bubble burst all those years ago and as a result of a declining population houses on the whole only depreciate in value. So this will often mean people will try and do everything as cheap as possible as there's little reason spending up big on something you'll never get your money back on in the future.

The ski area I work at is actually one of the few places in all of Japan that has seen some pretty good growth in the housing and land market over the last decade. When I first came here you could get land in the village for as little as Y50,000 per tsubo. Now you would struggle to find any land under Y250,000 per tsubo. Some land in parts of the upper village is going for over Y700,000 per tsubo. Many houses have been built here in recent years worth over $1 million dollars. The penthouse in one of the properties I'm involved in sold for over $3 million. Wasn't that long ago you could have bought whole parts of the ski resort for that sort of money. Pretty much all of this growth has been driven by foreign investment though.

Be very careful of humidity in Japan sans Hokkaido. It's easy to stuff your walls with glass fiber. It is not easy, however, to control humidity and condensation.

Humidity can be an issue up here too cranks. This last summer many people had issues with mould forming in their houses.

Wow, if even Hokkaido, where there is no 梅雨, has the problem, no wonder some houses down there in 本州 are literary eaten by mold.

You've got a nice stove anyway :)

Cranks, incidentally I live in one of the most humid areas of Japan. We get rain virtually every day (even if it's just a little). The room that I have my insulation in has very poor circulation... but even still I have had less mold problems since I hung my fiberglass (I say hung because I had frames built, covered my insulation panels with polyester batting and then with cloth and put them on the frames). I also installed an air conditioner which I run pretty much the whole time whenever I got there (it's a heater during the winter of course).

I've actually read though that insulation can't get moldy... however, dust particles can. So after years and years of particle buildup, mold can actually appear in glass fiber. I'm hoping my polyester batting and cloth covering will alleviate this possibility from becoming a reality!

I remember one time I had one of those particle board pieces of furniture in the room I'm talking about... after a week or so of summer it was literally covered in mold. We also built some bamboo skiis and those got completely covered in mold as well during the summer. I think that is one of the good points of styrofoam insulation... I don't think it can get moldy. That is if I am remembering correctly of course.

I`m going to agree on the mold - insulation makes it VERY hard for a house to naturally dry out... And over the years the moisture that becomes trapped beside the insulation will really destroy the house. That is part of the reason that insulation options are limited - the ones that are used tend to have serious testing and treatments done to them to prevent any increase in moisture.

As for "eco" - if you aren`t trying to heat/cool the space to begin with...

Most people don`t, really. They use heaters in specific spots to heat them and not much else, and use AC so sparingly that it seems like a crime to say you turn it on at all.

Regarding house value and the bubble - the bubble really has nothing to do with it. The value of buildings did nothing but depreciate LONG before the bubble. It`s been that way since at least the 1960s - likely long before, as one of the big reasons people cite for not wanting to live in a house someone else has lived in is ancestors. Tradition says not to live somewhere a non-relative has put an altar to deceased ancestors. In other words, pretty much any "used" house.

Currently, the growth in land prices is dependent on new development. Popular suburbs are shooting up in price, bubble inflated to begin with inner city areas and villages with few job opportunities are dropping. When we bought this room 5 years ago, the area around was about 180,000/tsubo on average. Now it`s 400,000, and painfully reflected in our property taxes. On the other hand, small villages are often prepared to hand out land for free if you promise to actually live there with a family. It all depends on the area, the convenience, and the development/future development plans. Sometimes it even hinges on things that are remarkably silly. A good example was an area we looked at purchasing in before deciding on this one. There was a massive shopping center nearby - and then it closed for renovations without any indication of when it would reopen. About a year after closing, the property values in the area had dropped about a quarter. When it reopened with a new and fancy facade, the prices shot to double what they`d been before.
Nothing else had really changed.

Beware the space on the other side of the insulation. Mold in the room is easy to spot and take care of before it causes a problem. The big issue with insulation is that it tends to hide the mold behind it until it gets to the point of serious damage.