Kenji's second life began with a single, seemingly weak ability: water magic. But in this new world of fantasy, his old knowledge of Seiran's physics is the ultimate cheat code. He can weaponize a simple hydrogen bond and turn humble droplets into devastating deluges. This unprecedented power rewrites the very laws of magic, attracting the attention of kingdoms and ancient evils alike. As a forgotten Demon Lord stirs in the shadows, Kenji must ask himself: will his command of water save this world, or will it be the flood that drowns it?