We aim to explore the “mystery of life” at the molecular level by searching for novel functions of natural proteins and by artificially modifying or designing functional proteins. For example, in our investigation of new functions of natural proteins, we discovered that aminoacyl-tRNA synthetases, which play essential roles in protein translation, are secreted from cells and, upon cleavage, act as cytokines and regulators of angiogenesis. We are currently continuing our efforts to elucidate the molecular mechanisms underlying these noncanonical functions. Furthermore, we are investigating the molecular evolutionary inevitability behind the acquisition of these noncanonical roles. As part of our research on the artificial design of novel proteins, based on the “molecular evolution hypothesis” that proposes proteins with diverse functions can evolve through the modular shuffling of structural and functional domains, we aim to create novel proteins capable of regulating cellular differentiation, apoptosis, and development.