Aaah, thank you for those kind words, I'm most happy you added the anime to your watch list! (And yes, it is based on a novel entitled Die Schwarzen Brüder! Haven't read it yet, but for what I know, the anime looks like the superior version of the story haha).
And that's exactly it: the idea of living through the hearts of the people who love you, and making the people you love live within yours is something very core and very touching to the anime!
And thank you for playing this game!