If it's Thursday, it must be Japanese.

Today was day one in the Paris marathon of spring fashion shows. And, as in the past three seasons, the first day was reserved for the new wave Japanese designers.

When they first asked to show their collections on the French designers' turf, they were put on the schedule for Thursday, a way of tucking these outsiders into an offbeat day. They could act as a curtain-raiser for the week's events, showing their creations before many buyers and press had settled in for the usual run of shows.

But right away these Japanese collections proved to be among those no one could afford to miss. And Thursday became one of the more crucial and crowded days of the French ready-to-wear showings. Even President Mitterrand recognized the importance of the Japanese shows -- he scheduled his reception at the Elyse'e Palace to kick off this season for Wednesday night.

The new wave Japanese designers -- particularly Rei Kawakubo of Comme des Garc,ons and Yohji Yamamoto -- have changed not only the schedule of fashion but the look of it. "They have given us another concept of what is beautiful," said designer Karl Lagerfeld, "a new way to look and design clothes."

The influence of the Japanese designers -- with their formless shapes, askew closings, up-and-down hemlines and intricate, unfamiliar textures -- has been so widespread that today, when Kawakubo's collection was presented in the first show of the day, the clothes looked almost familiar. So many designers in France and Italy, as well as New York and California, have been influenced by these designs that some of the styling is approaching mainstream.

Of course, the Japanese designers have changed, reversing their penchant for obscuring the body with slimmer clothes, and injecting some color into the once characteristically black and gray schemes.

Many of the clothes Kawakubo showed here were downright conservative -- sundresses with cutout backs, tunics with stitched down pleats and even shirring to define the bosom on a loose top. But there were also turned-under hems that rounded the bottom of her clothes, very much apart from the norm.

There was more color than before in this collection -- particularly pink and brown -- as well as the expected indigo, a favorite color in Japan, and black, the noncolor that has been a major part of the Japanese look for several seasons.

In dramatic contrast to the oversized and long clothes that virtually concealed all signs of the female form, Kawakubo included some above-the-knee hems and body-revealing, deeply cut armholes and backs.

"The collection was easier to understand, more realistic to think of wearing," said Jessica Mitchell, a Saks Fifth Avenue vice president who is originally from Washington. "The typical outsized shapes looked old, and the new cleaned up, simplified shapes, particularly in the dresses and jumpers, were beautiful."

While designers in general have been swinging back to more shapely styles, clothes that reveal the body, through cut or cutouts, are a dramatic change for the Japanese.

"The Olympics have made the Japanese more willing to show the body," said Issey Miyake, the Japanese-born designer who has shown his collections in Paris for more than 10 years. "Japanese men and women do not like to look at the body. They do not admire the body . . . Until the Olympics and the display of firm muscular bodies of the athletes, the Japanese have preferred to keep the form hidden."

Designer Junko Koshino was far less successful in her attempt to reveal the body than Kawakubo. Her designs were more a parody of cutouts, as in her bathing suits -- like diver's suits on which someone had gone berserk with a pair of scissors. Models with shapes had trouble staying within the bounds of the fabric.

But by afternoon, when Yohji Yamamoto sent his clothes down the runway, it was clear that this designer, too, was in complete control of a new, more appealing Japanese style. Everything started very narrow across the shoulders, and then seemed to free up as the clothes moved down the body. Even when the fit was tight to the torso, there was draping and shaping to gave the clothes a decidedly modern street-urchin look -- a Japanese translation of Dickens.

Both Kawakubo and Yamamoto like patterns, but it was Yamamoto's variation on tapestry designs that the audience loved.

"It is wonderful for Washington, except where it got very tight over the derrie re," said Henri Peker, who owns La Boutique Francaise with his wife Michelline Peker. He wasn't sure his customers would go for the cutaway jackets with a ducktail effect. "That's for New York, not for Washington," he teased.

"But all the rest . . . it's wonderful. It's almost conservative and wonderful," Peker said, adding with a smile, "almost not too Japanese."