Complex sentence: Stranger released his debut mixtape, "No Stranger To This", which was put together in the course of seven days and officially released on December 11, a day before his debut album, "Journey Begins".
Split into simpler sentences: Stranger released his debut mixtape, "No Stranger To This". It was put together in the course of seven days and officially released on December 11, a day before his debut album, "Journey Begins".