Premise: "Maji Desu ka Ska!" (まじですかスカ! , Maji Desu ka Suka! , "Seriously, Ska!?") is the 45th single of the Japanese group Morning Musume, released on April 6, 2011 on the Zetima record label. The single sold 33,698 copies in its first week, charting at #5 on the weekly Oricon singles charts and peaking at #7 on the Japan Billboard Hot 100.
Hypothesis: Zetima record label had a number one billboard hot 100 single.