Boko Haram insurgency insurgency spread to neighboring Cameroon, Chad, and Niger thus becoming a major regional conflict. In 2015, a coalition offensive forced Boko Haram to retreat into the Sambisa Forest. The insurgency took place within the context of long-standing issues of religious violence between Nigeria's Muslim and Christian communities. Boko Haram has been called the world's deadliest terrorist group, in terms of the number of people it has killed. Nigeria was amalgamated both the Northern and Southern protectorate in 1914, only about a decade after the defeat of the Sokoto Caliphate and other Islamic states by the British which were to constitute
Angel Sanctuary actually a living angel." The original title for the series was "Coming of the Seraphim", which Yuki later decided against in favor of "Angel Sanctuary", as she thought that "angel" should be included in the title and "sanctuary" had a sense of something "forbidden" or "against God". She decided to set "Angel Sanctuary" in Japan in "near future," partially because the setting would be largely unchanged and partially because she had a wish to draw modern clothing styles and sailor uniforms. As she had been already working on a successful serial, the gothic mystery manga "Earl Cain", she faced opposition