More than 100 people gathered at Mt. Fuji Japanese Steakhouse in Hillburn Sunday to celebrate the opening of Y’s Lounge, a sleek and intimate dining area for Japanese fusion cuisine, bar, suites of couches, and a killer view of the Ramapo River and the green valley. The addition marks the 50th anniversary of Mt. Fuji Steakhouse restaurant, a destination for Japanese Hibachi cuisine. Yoshimasa Tada and Nancy Fujita, the founders’ daughter, own and run the restaurant that was built by Fujita’s parents, the late Tokuaki “Tony” Fujita and his wife Kazue.