The Ōtsuzumi(大鼓,Ōtsuzumi?), also known as the ōkawa, is an hourglass-shaped Japanese drum. It is a larger version of the tsuzumi, or kotsuzumi and is used in traditional Japanese theater and folk music. Its appearance and the sound it produces are slightly different from that of the tsuzumi. Whereas the tsuzumi is smaller and has a more ornate drum head, the okawa is larger, and its head takes on a more plain, leathery appearance. The sound is also higher and sharper in pitch, resembling more of a "pop" than the tsuzumi's "pon" sound. The hourglass structure is slightly bigger, and the heads of the drum are taut very tightly. The okawa is played on the side of the player, possibly due to its larger, heavy size, whereas the tsuzumi is played upon the shoulder.
Care for the drum heads of the ōkawa is peculiar in that they must be kept dry at all times. In contrast, the heads of the smaller kotsuzumi must always be moist. Since the sound of the ōkawa is supposed to be higher in pitch, the player must ensure that the skin of the drum-heads remains as constricted as possible, and this is best realized when the drum heads are kept dry. To keep the drum heads dry, they are often kept near a kind of old style of Japanese furnace called a hibachi. When the player is ready to perform, he takes the drumheads and binds them to the body of the ōkawa as tightly as possible. Given the nature of the heads of the ōkawa, they wear after a specific number of times. Since they are very expensive, at least a thousand US dollars a pair, the ōkawa player must measure how many times, and how long he plays his instrument. If he takes good care of the heads, he can use them for as much as ten performances, after which the heads show sign of wear, they lose their desired sound quality, and they must be discarded.
Like the tsuzumi, the ōkawa is also struck with a player's bare hands. As the drum heads are taut very tightly, it often hurts to play the drum, and the player must develop calluses on his fingers to play comfortably. The player must take care of his calluses, taking a knife and shaving them off from time to time before they get too big.