Nangis was born on the island of Guadeloupe, where he began playing football at the age of six years. In 2009 he moved to SM Caen on the French mainland. Only 16, he was appointed to the second team and played from then on in the fourth division. In 2011, he signed as a 17 -year-old a three-year professional contract for Caen. In his first season, he played eleven top-flight, but was still employed in the second team. In 2012 he suffered relegation to Ligue 2.
Nangis debuted on 29 September 2009 as a 15 -year-old in a 6-0 win against Wales for the French U-16 national team. He remained scoreless while, but he scored on his second deployment on 1 October in a 5-1 against Wales three hits. From then on he played for other national youth teams, including the U- 17, with which he participated in the World Cup 2011.