Recently, we developed a Na-flux point seed technique for fabrication of large-diameter gallium nitride (GaN) crystals with low dislocation density. It may be possible to further reduce the dislocation density of crystals fabricated by this technique by reducing the point-seed (PS) density, because one dislocation remains on the c face of each grain grown on each point seed. Therefore, in order to realize coalescence growth by using a Multi-PS- GaN substrate with a low PS density, namely a long interval between neighboring point seeds, the lateral growth of each grain grown on a point seed must be enhanced. We attempted to promote the lateral growth of GaN crystals grown on a point seed by decreasing the flux thickness. As a result, we realized a high growth rate of 80 mu m/h along the a direction and a low aspect ratio by the Na-flux point seed technique. Moreover, almost no dislocations could be found in the lateral growth sector. Consequently, growth in a thin flux is applicable for the coalescence growth technique with low PS density and may be an outstanding approach for reducing the dislocation density in GaN crystals grown by the Na-flux coalescence growth technique.