Sentence:  It thus follows that if Ryuji and Noboru are two halves of one person, Ryuji's murder is a "<WSD>self-rape</WSD>" or self-killing, a "suicide." (It is perhaps in this sense that every murder is a "suicide." 
Meaning of the word marked with <WSD> tags:  An act of rape where the rapist identifies with or is the same as the victim.