About halfway through the series, I thought Shun had killed himself in order to prevent any further damage to others.
However, in the last few episodes, Saki hears his voice as he gives her some very important advice. In the second to last episode, she even seems to see Shun in front of her. However, he seems to disappear in an instant, and she sees Kiroumaru instead. She later hears his voice once more as he tells her the solution to get rid of Maria and Mamoru's child.
Were these just hallucinations, or was there some supernatural force going on?