5317 page 11: Hoshi Execution 『15-0』

a point in tennis is 15. the 15 students vs hoshi thing. 0 is read as "love" in tennis. hoshi does not have anyone to live for/loves.
also 15-0 is no where near a match point. showing how hoshi will never see the end of the (koroshiai/death) game because he lost.
metaphors.