Washington's National Symphony Orchestra earned an enthusiastic critical reception from reviewers on its tour of Japan this week although it played to a good many empty seats.

Critics in Osaka and Nagoya praised the orchestra's liveliness and originality, calling performances in those cities distinctly American in flavor. "A really American style of playing," was the headline over a complimentary article in a Nagoya newspaper, the Chunichi Shimbun.

The orchestra, led by music director Mstislav Rostropovich, left Tokyo this morning to continue a five-nation Asian tour that will take it to includes Manila, Hong Kong, Taipei and Seoul.

The major Tokyo performance of the symphony was in the Tokyo Bunka Kaikan, probably the best large hall in Japan, and it was about two-thirds filled. The audience, however, was enthusiastic, and Rostropovich was called back onstage for five extra bows after a performance of Shostakovich's "Symphony No. 8.."

The conductor surprised many by declining invitations for an encore.

The other two Tokyo area appearances were in small college auditoriums, a fact explained by the tour's local sponsors as due to scheduling difficulties.

The reviewer for Chunichi Shimbun was delighted with a rendition of Beethoven's "Eroica," calling it "clear-cut, bright, dynamic performance. This is really American."

The critic, Tomoaki Fujii, said it differed from the "intellectuality" of other orchestras' versions, but said the "entire hall was dominated by the grandiose colorfulness and overwhelming volume of the sound."

Fujii commented that as one of the world's finest cellists, Rostropovich had sought to build the orchestra's string section to an exceptionally high level and his success in doing so had been demonstrated by the performance of Barber's "Adagio for Strings."

In Osaka last week, the orchestra was part of that city's 25th annual music festival. Rostropovich had performed at the first of those festivals with the Leningrad Symphony Orchestra.

The critic for the Osaka editions of the national Asahi newspapers was restrained but generally admiring, referring to the "stable quality and technique" of the orchestra.

The critic, Takao Oono, praised Rostropovich for not forcing the orchestra to excite the audience and for "faithfully expressing" the central themes of each number.

"There was music by Russian artists, but Rostropovich does not try to show off his blood relations with the Russians," commented Oono. "But he certainly has a strong sympathy with them in the broadest sense."

Perhaps the most aroused critic was the Nagoya Asahi Shimbun's Sadatada Maki, whose summation was headlined simply: "Overwhelming. Tremendous." Maki admired the technical dexterity of Mussorgsky's "Pictures at an Exhibition," referring to one passage as "an explosion of sound led by the percussion."

Maki summarized it all: "I felt the happiness of liberation throughout this concert."