B'z is Tak Matsumoto (松本 孝弘 / Matsumoto Takahiro; production, composition & guitar) and Koshi Inaba (稲葉 浩志 / Inaba Koshi; lyrics, vocals). They are known in Japan for being the most successful Japanese rock band ever by selling over 79.3 million records only in Japan. Since their single "太陽のKomachi Angel" (Taiyou No Komachi Angel), all their releases have debuted at #1 on the Japanese Oricon charts.