In the very first strip of the Suicide Girl storyline, Shiunji specifically asks Yuuko if she wants to have sex before she jumps. It's possible that he was merely pretending to be into necrophilia as a plot to prevent her suicide. His tears after her death are genuine tears of sadness, but that's also exactly when he snaps. His necrophiliac father's influence finally catches up to him, and he has never looked back since, as evidenced by Mr. Watanabe saying he knew he didn't raise his son to be a "quitter." Now, why would he have that sort of reaction if Shiunji was already a necrophiliac? He must have been proud that his son finally accepted and expressed a desire to share his fetish, and one strip later, we see that Shiunji has only just decided to learn about taxidermy, and he later call