There is a special poignancy in the vintage films of a nation that was an enemy.

For an American brought up in the '40s, the Japanese were a jungle people, savage and simian, manicacal in their devotion to a bloodthirsty emperor. Of course, we have long since awakened from that particular dream of hate. We know now that we were fighting city kids and farmers and students like ourselves.

Just the same, the current American Film Institute series on Japanese films-of-the-year, 1931 to 1978, has a message for those who fancy themselves immune to propaganda.

Had we realized how very westernized Japan was, even in the '30s? How adults sang "My Blue Heaven" and ran home movies and patterned their comedies on Pagnol and Rene Clair and Chaplin? How small boys in shorts wore their socks lowslung and sloppy just like American kids? Could we have imagined that in 1938 Japan could produce a war film in which no one gets killed, essentially a pacifist protests against the military bloc in charge?

"Five Scouts" (tonight at 8:45) is a laughable compilation of clinches, true, leaving the impression that soldiers who invaded China in 1937 were the weepiest army on record, but it is interesting to learn that this movie was banned in Japan for many years.

The other half of tonight's double feature is "A Ball at the Anjo House," a sort of Japanese "Cherry Orchard" -- also related to Satyajit Ray's "The Music Room" and Visconti's "The Leopard" -- depicting the decline of a great aristocratic house. Made in 1947, in a defeated country, the film refers to black marketeers and show the rise of a new industralialist generation.

Some of the finest directors are represented in the 15-film series, which-features a number of important pictures never seen before in this country. Of special interest in "The Profound Desire of the Gods," by Shohei Mamura, who has been called the greatest Japanese director since the '50s and "one of the unsung masters of world cinema." This film (shown Oct. 29 at 9 p.m.) shows how a primitive island culture was introduced to industrial society. It appears to symbolize the Japanese ambivalence to losing its traditions to technology.

The famous but rarely screened "Red Beard" by Akira Kurosawa, a three-hour examination of compassion and its final inadequacy, runs Oct. 26 at 9 p.m. Starring Toshiro Mifune as a tough but totally dedicated doctor, it goes beyond sentiment and the happy ending to teach something about acceptance.

"Darkness at Noon," Monday at 6:30 p.m., is a 1956 retelling of a celebrated 1951 murder case, a Japanese Sacco-Vanzetti trial. Even today in Japan, the film is controversial, though the accused defendants were exonerated in 1968. The question is: Did it help them or hurt them?

That picture and the 1961 "Bad Boys" (Friday at 6:30 p.m.) seem to be the tip of an iceberg as Japanese society coped with a younger generation that not only refused to honor its ancestors but mugged old ladies. "Bad Boys" is about life in a reform school and apparently belongs in a special class of movies about Japan's attitudes to crime, criminals, would-be criminals and sassy kids.

The series includes so many rarities that even area experts in Japanese film are having a field day.

Interestingly, the Biographer Theater is also having a Japanese series, running even longer, through Nov. 20, and including 13 Washington premieres. About half of these pictures are the classic samurai epics, usually featuring the durable Mifune, but there are also a number of important modern Japanese works.