We study how the brain develops and functions at molecular, cellular, and genetic levels using zebrafish. We use microCT imaging at SPring-8 and reproduce transgenic fish in which activation of each neuron and animal behavior can be controlled by light. Zebrafish is one of the best subjects used in place of vertebrates and human beings, due to its transparency at early stage and rapid growth. You can perceive the mystery of life not only in the brain but also in the development of muscles, bloods, bones, heart and other organs. We also aim to elucidate evolution of the brain by studying mice and ascidians.