'たのしみ' - The thing I noticed about this was that 楽しみ was written in hiragana. Why? Possibly because there are two kanji which can be used for たのしみ, either 楽しみas above or 愉しみ.
Straight 楽しみ seems to be more appropriate when designating simple fun or enjoyment, as in light recreational enjoyment with no other dimension to it, plain and simple, whereas 愉しみ would appear from my cursory dictionary investigations to imply a deeper kind of enjoyment where the sufferings or troubles of the heart are lifted, or that the enjoyment has a deeper dimension, such as reading a book as opposed to larking about with a bat and ball in the park on a sunny day.
This leads me to speculation as to why, other than the obvious one of leaving it to the readers discretion or imagination, the writer did leave it in kana. It seems that 愉しみwould make more sense in the context of the epigram, as in the deeper enjoyment of escape from punishment as opposed to escaping for mere amusement or boredom. Perhaps there is the hint that it could be either, and a indictment of the human predicament position in an 'absurdist' universe. Even simple fun, anything to escape reality or boredom being as valid as a deeper from of healing of the pain of existence. The second part of the variant kanji (ュ）representing the sound part 音符 of the kanji has connotations of healing and even allusions to kanpo 漢方Chinese medical terminology - again pushing me towards wondering why Abe didn't just plum for this as opposed to simple 楽しみ. Here we are right at the start of the novel and its already a strange and odd world!
It struck me as a remarkable orthography