Nkechi Ka Egenamba, known as Ninja, is an English rapper and the female lead vocalist for the British indie band The Go! Team. Doing a mixture of rapping, chanting and singing, Ninja is well known for her energetic stage performances and dancing. In 2005, NME voted Ninja the 15th coolest person in music.

Proof of Youth is the second studio album by English band The Go! Team. It was released on 10 September 2007 in the United Kingdom by Memphis Industries and a day later in the United States by Sub Pop. Proof of Youth was preceded by two singles: "Grip Like a Vice", released on 2 July 2007, and "Doing It Right", released on 3 September 2007.