THE Hongkong Academy for Performing Arts and Alliance Francaise de Hongkong are presenting a new musical event, ''BNP Music Classics'', an annual concert featuring winners of the Long-Thibaud International Competition. This year's performer is Japanese pianist Midori Nohara, who gives a recital on May 22 at 7.30 pm at the APA Concert Hall. Nohara graduated from the University of Fine Arts where she received the Gold Medal. In 1987 she won first prize in the National Piano Competition in Japan and also the Masuzawa Prize for best performer. In 1990 she went to Paris to further her musical studies where she won the Long-Thibaud International Competition. Her programme on May 22 includes Bach's Chromatic Fantasia and Fugue in D minor , Ravel's Jeux d' Eau , Liszt's The Death of Isolde, La Campanella and Ballade No 2 , Prokofiev's Sonata No 3, Chopin's Ballade in G minor and Sonata in B minor. Tickets at $50 (adults), $20 (full-time student and senior citizens) are available at all URBTIX outlets. For telephone reservations call 734-9009. The concert is part of the Festival Le French May and is sponsored by Banque National de Paris, Hotel Conrad and Fimoxy Nacs Ltd.