Based within the Tanaka Group at Kyushu University, Hydrogel Biointerface Design Team develops next-generation biomaterials by designing smart hydrogel networks and biointerfaces that precisely control what cells “feel” in both 2D and 3D environments. We integrate polymer synthesis with supramolecular and chemical crosslinking strategies to engineer key interfacial cues—especially the hydration state and water structure at polymer surfaces—together with mechanics and molecular presentation, thereby directing stem/stromal cell morphology, differentiation, survival, and immune interactions. Building on these hydration-guided design principles, we create modular platforms such as protective polymer shells, microgels, and click-chemistry-enabled surface modifications to improve therapeutic cell retention and function, while also translating our technologies to biomedical device applications involving blood– and tissue-contacting materials.