[en] Large-area EC experiment at Mt. Fuji aimed at the research of nuclei interaction in 10¹⁵ eV region through the observation of γ-ray families with Σ E sub(γ) exceeding 100 TeV. EC is thus deployed on a scale beyond 100 m²; the exposure up to the present is about 550 m².year. In the statistics of large γ-ray families, about 60 have been already analyzed among almost 100 in total. Energies of primary cosmic rays giving rise to such families are in 10¹⁵ - 10¹⁷ eV region. The corresponding AS sizes are 10⁶ - 10⁷, which are equivalent to EAS phenomena. (Mori, K.)