information before the story

Sawada Tsunayoshi and his guardians was killed by a mysterious group of people.

Primo give a chance for sawada tsunayoshi to protect the vongola by transferring his soul in a parallel world wherein he have two younger brother. Sawada Hibiki and Sawada Tsumino.

In that world he one of the best hitman and assassin in the mafia world named Sora27. He acts dame in school and home eventhough his brothers knows his true nature.

Is there any reason for his brothers to hate him? What happened?

As he struggle to adjust in this new world. what kind of situation can happen? When all his guardians revived in this world too without him and them knowing.??!!