But I'm Dame-Tsuna!

Tsunayoshi Sawada or Vongalo Decimo who is 15 was called back to the past by Giotto or Primo. Tradegy was going to strike so Giotto sent Tsuna back to protect his past self. He had identification to prove he was supposed to be there and not to raise suspicion and Primo and his Guardians questioning, why is this boy so skilled?