Lead actor Yoo Hae-jin of the controversial film “The Assassin(s)” said he will take a firm stance against protesters who gathered outside his Seoul home over the weekend, his agency said Monday. VAST Entertainment said it was taking the matter seriously. “We will take a firm stance against any actions that violate the actor’s privacy, threaten his safety or tarnish his reputation,” the agency said in a statement. The agency added it was collecting relevant online posts and other materials and would take all necessary measures to protect Yoo’s rights and safety against illegal acts. On Sunday, members of conservative civic groups held a protest near Yoo’s home in Seoul’s Seongbuk District, calling for the film to be pulled from theaters and demanding apologies from its cast and production team. “The Assassin(s)” centers on the 1974 assassination attempt on then-President Park Chung-hee. Park survived the attack, while then-first lady Yuk Young-soo was killed. An official investigation concluded that Mun Se-gwang, a Korean resident of Japan, acted alone under instructio