*** 1/2 MASE “Harlem World” Bad Boy/Arista

With the exceptions of Erick Sermon and Too Short, no one with a flow as slow and nonchalant as Mase’s has succeeded so well in a genre where testosterone and icy menace are king. As a writer and/or performer on such hits as Puff Daddy’s “Can’t Nobody Hold Me Down,” the Notorious B.I.G.’s “Mo Money, Mo Problems” and Mariah Carey’s “Honey,” the 20-year-old musician has already established a high hip-hop profile. His debut album, which entered the national sales chart at No. 1 last week, proves that it’s no hype.

Mase is consistently mellow and confident, relying on simplicity but also displaying moments of stunning insight and poignancy. In “What You Want,” he drops his “player” hat and reveals a sensitive and loyal man--it’s so charming that you almost forgive him for the subsequent “Cheat on You.” In “24 Hrs. to Live,” he and some pals contemplate what they would do with their last day on earth, and they go touchingly beyond the predictable sex scenarios.

With “Harlem World,” which features production from a host of hot studio hands, including Sean “Puffy” Combs, Mase manages to display commercial sensibilities without selling out, and he’s also able to poke fun at his own image when the time is right. For Mase, mo money seems like no problem.

Albums are rated on a scale of one star (poor) to four (excellent).