When a plastic bottle with water is placed upside-down with a thin pipe at its head. limit-cycle oscillation call be observed. A simple differential equation can reproduce the properties of this oscillation. In the present study, a three-coupled-oscillator system is investigated experimentally and numerically. The behavior of the three coupled oscillators with frustration is interesting from the viewpoint of mathematical physics, and with all increase in size, this system should be helpful in unconventional computing, such Lis in, for example, optimization problems.