K-pop giant BTS has claimed its seventh No. 1 debut on the US Billboard's main albums chart with its new album, "Arirang." "Arirang," the band's first group project in three years and nine months, debuted atop the Billboard 200 for the week of April 4, Billboard said in a chart preview released Sunday (US time). It marks BTS' seventh No. 1 debut on the chart, following "Love Yourself: Tear," "Love Yourself: Answer," "Map of the Soul: Persona," "Map of the Soul: 7," "Be" and the anthology album "