[Subaru looks away for a moment, before nodding. The camera angle keeps shifting funny-- it looks like he might be fidgeting with his hands.]

...My family-- the Sumeragi family-- is an old family that has worked as... We work with spirits. We help spirits pass on, ensure no harm comes to the living. I was chosen to be the head of the family, due to my powers.

...there's another family-- the Sakurazuka family. They're a clan of assassins. They use the same magic we do, but they don't do good things with it. We've been enemies for generations.

He was going to kill me, because I was the head. He accepted Hokuto in my stead... But he's killed thousands more since then, and he'll keep doing it if someone doesn't stop him.

[there's a lot more still to the story-- a lot of parts he's left out-- but that's the basic premise.]