Ever since the School Island Incident, in which the four Kings were involved, the Silver Clansman, Kuroh Yatogami and Neko were on their search for their master Shiro. Unable to find any leads to Shiro, the two were in a gloomy mood until they ran into HOMRA members, Rikio Kamamoto and Anna Kushina who were apparently being chased by someone... Source: crunchyroll