As the latest effort to search for deeply-bound
-nuclear states, E15 experiment has been carried out at K1.8 branch beam line (K1.8BR) at J-PARC. 3He(K−, N) reaction was employed to search for the simplest
-nuclear bound state, K−-pp. In this proceeding, preliminary results of 3He(K−, n) spectra obtained in the first physics-run will be presented.