On 26th November 2004, SINTEX-F1 workshop was held at the Hakone Prince Hotel. The aims of this workshop were to discuss intensively further improvement of physical performance and optimization on the Earth Simulator of the SINTEX-F1 model developed as a part of the research collaboration with EU-JAPAN, among researchers involving in the projects. In the workshop, the Program Director Dr. Yamagata, one of the main organizers of the workshop, introduced the key role of SINTEX-F model for introducing importance of Indian Ocean dipole (IOD) in the world. He also discussed some basic ongoing researches for future predictability experiments. IOD is considered basically as an atmosphere-ocean interaction phenomenon in the tropics like as El Nino Southern Oscillation (ENSO). However, it turned out that its prediction is relatively difficult compared to that of ENSO because of crucial differences between the Indian Ocean and the Pacific Ocean such as geographical conditions, which activate scale interactions over the Indian Ocean. Dr. Navarra of Istituto Nazionale di Geofisica e Vulcanologia (INGV), the representative of the SINTEX project in the EU side, had an overall review of research activities about prediction methods. Then, other participants reported recent research outputs such as a seasonal forecast, the Indian monsoon, as well as progress in development and improvement of the models. Finally, it was confirmed with EU side to make active contribution for the Indian Ocean modeling project by promoting joint development and improvement of physical and computational performance of SINTEX model.