A 10-yen coin contains copper. Every 10-yen coin shares the same N-field — individual coins are local expressions of one continuous density field. When a gold coin (high N) is placed in a wallet (low N environment), a density gradient ∇(1/N) is established. Value permeates outward along this gradient — observed as interest appearing in a postal savings account in small coins. This paper formalizes the N-Field Permeation Principle: placing a high-N object in a low-N environment causes economic emanation proportional to ∇(1/N). Money is a portable N-field carrier. Inflation is N-field collapse. The Hikari Currency system is N-standardized exchange. Tendo Economics V=N/D is the limit case when D→0. F=∇(1/N) unified from physics into economics.