Premise: 69 (シクスティナイン , Shikusutinain ) is a roman à clef novel by Ryu Murakami. It was published first in 1987. It takes place in 1969, and tells the story of some high school students coming of age in an obscure Japanese city who try to mimic the counter-culture movements taking place in Tokyo and other parts of the world.
Hypothesis: 69 is a title with only numbers.