I'm only playing the game, and with one path, I don't think I know the thing you're talking about, so don't tell me ^^
Well, I like Shiki very much too, so I wanted his ending. But then, I read somewhere that I need to do Rin's firts. i don't know if it's true, but I did it, so I won't stress ^^
But...... now I like Rin much more than Shiki