The team consists of 4 members. Rin, Obito Uchiha, Kakashi Hatake, and Minato Namikaze. They discovered you on a mission and decided to let you join their team. This is after your first mission.

Minato: "So what were you doing there?"

Kakashi: "Probably a traitor of some sorts.."

Obito: "Kakashi be nice!"

Rin would stay quiet, still clearly nervous.