There is a video available on YouTube ("In Japan Moving is Less of a Chore and More of an Art"), sonorously narrated by an English gentleman, that explains in detail the wonderful services Japanese moving companies offer. Not only do movers pack and unpack belongings, they clean those belongings before and after moving them, bring their own special boxes, affix protective panels to walls and corners to prevent damage and even put on disposable socks before entering a residence. Moving companies in other countries don't offer these services, at least not without charging extra for them. Moreover, Japanese movers are without exception polite and helpful, and they don't expect a tip.
Forty years ago, moving house in Japan was basic. You rented the services of a truck and a driver. Everything else you did yourself. But the housing boom of the 1970s and '80s, along with the attendant increase in consumption, gave rise to moving services that offered more. There are now about 200 moving companies in Japan, and almost all offer a wide range of services. Those mentioned above are considered a kind of standard, but companies can also compete by offering savings to customers who aren't necessarily looking for them.
The fiscal year in Japan starts in April, so January to March is peak moving season. That doesn't mean it's more expensive to move during this time period, but it does mean it may be more difficult to take advantage of special offers. We recently moved in the middle of this season, but because we weren't going far, we looked for companies that offered savings for short moves.