Toshiko Akiyoshi is one of jazz's more intriguting phenomena, in that she single-handedly gives the lie to so many misconceptions all at once. She did not move to America (from Japan, where she had moved from her native China) until she was in her mid-20s--yet she plays a distinctly American brand of jazz piano with no "accent" whatsoever to her music. She has established herself among the music's most innovative composer-arrangers for jazz orchestra, not to mention big-band leaders--both realms considered to be the province of males. Among the obvious inspirations from which Toshiko draws are the wide tonal palette of Ellington; Japanese ceremonial and folk music; the cool of early-60s Gil Evans; the chordal wizardry of the post-beboppers; the arranging stratagems of Thad Jones; and the intricate, convoluted melody lines of Lennie Tristano. It's a diverse list of ingredients, but Toshiko obviously has the recipe: her best work blends it all into a charismatic (if sometimes rather busy) repast. There's a tendency, when discussing Toshiko, to home in on those pieces that explore traditionally based Japanese themes. But you do so at the risk of bypassing her stomps, shouts, and flag wavers, which similarly honor and advance the jazz tradition that she has fully adopted. Sunday and Monday, Joe Segal's Jazz Showcase, Blackstone Hotel, 636 S. Michigan; 427-4300.