Light-emitting molecules have been extensively studied due to their potential and wide variety of applications from optoelectronic devices to biomedical applications. To fully understand and rationalize the light-emitting process for innovation of next-generation applications, it is vital to reveal the dynamic behavior of excitons, where excited electronic states (locally excited, charge transfer, and charge separated states), spin multiplicity, and motion of atomic nucleus are interacting each other. Here, we will show our recent progress on light-emitting systems developed under the "Dynamic Exciton" project in Japan.