Most of the crystalline materials used in the world are made by crystal growth from the liquid phase. In order to realize a high-quality crystalline material with few crystal defects, it is necessary to clarify what kinds of phenomena occur at the solid-liquid interface in the process of crystal growth and to clarify their fundamental mechanisms. For example, Fig. 1 shows the results of observing how the flat solid-liquid interface changes to a zigzag interface. It can be seen that different solid-liquid interface shapes are formed depending on the type of material. In addition, the conditions under which the solid-liquid interface shape changes also differ depending on the material. In our laboratory, we investigate the dynamics at a solid-liquid interface including not only the interface shape change but also how crystal defects such as grain boundaries, twin interfaces and dislocation clusters are formed. Based on such fundamental knowledge, we create practical large-scale high-quality crystals and unprecedented crystalline materials, as shown in Fig. 2. We aim to contribute to the sustainable development of human society via crystal growth study.