Commissioned by the NTT East Tokyo Wind Ensemble "Tetrardus" is Greek for "fourth". In the work, the pitch of 4th and the sound centered on the turning pitch of 5th blend the difference between tonality and dissonance. That creates the overall piece. Since the music has a story-like quality, we expect each performer to reveal their own unique character. Being sensitive to the tone and balance of the percussion will be an important contribution to the performance. I would like to express my sincere gratitude to Mr. Masato Sato, a band director, for his advice in completing the work.