By Susan Moffat

(FORTUNE Magazine) – The Japanese, famous for saving, are now loading their future generations with debt. Nippon Mortgage and Japan Housing Loan, two big home lenders, are offering 99- and 100-year multigeneration loans with interest rates from 8.9% to 9.9%. Borrowers put up their homes as collateral. Such deals represent sound fiscal planning for some families, especially the very wealthy living in Tokyo who, perversely, can almost not afford to inherit a house: Japan's graduated inheritance tax can take up to 70% of a family's assets, including its home. Under the 100-year loan plan, a second generation can move into a deceased parent's home and pay inheritance taxes on only a fraction of the house's value. Most Japanese, of course, don't have such problems. Their challenge is to find a house they can afford, especially if they want to live in Tokyo. The housing crunch there inspired Robinsons on the Sand, a 1989 hit movie that's now No. 8 on Japan's VCR rental list. It tells the story of a salaryman and his family, who are willing to do anything to escape the misery of their tiny rented apartment. The ''anything'' turns out to be living on constant display as a ''model family'' in a spacious model home while potential buyers tramp through. Jealous neighbors bully the children and make obscene phone calls. Before long, one of the two sons turns delinquent, the daughter is killing kittens, and the father ends up homeless in the street. Mom and the kids finally return to their old apartment, where they watch TV in the closet in blessed privacy. So much for that particular family's Japanese dream.