*spoilers for Tsubasa Reservoir Chronicle and Tsubasa World Chronicle*
So I heard this song and thought it'd fit a character that lost and found a family. I thought of Kurogane from Tsubasa and Roy from Solty Rei. And I dunno why, but I thought angry, don't wanna be dad, become dad role, had to fit XD. I eventually ended up using Kurogane.
Basically it is about the events in Tsubasa told by Kurogane's POV. How he lost his family and found a new one along the way.