This research proposes a new practical approach for local residents who are at risk of a catastrophic tsunami. The approach is a unique composite of a computer simulation of a tsunami and collective evacuation behaviors, along with a series of workshops and evacuation drills to discover a feasible solution for successful evacuation without merely considering it a hopeless endeavor. The new tsunami estimation, reissued after the 3.11 catastrophe, is extremely severe, including warnings of 30-meter waves that could arrive only a few minutes after an earthquake. Given such dire warnings, people are likely to be too pessimistic and to feel hopeless in terms of evacuating after a tsunami. This research is aimed at developing an effective communication method, with the collaboration of a computer simulation, to encourage local residents in finding a practical and feasible way to evacuate and to avoid excess pessimism and hopelessness.