I feel stupid for only noticing it now but
Kaneki’s copy is only addressed to “Kaneki”
while Hide’ copy is addressed to “Kaneki Ken”.
The book in ch.31.5 is addressed to…yeah, “Kaneki Ken”.
(Ignore the “To Kaneki Ken” because it’s just a translation not present in the Japanese raws).
No doubt, it’s a birthday present from Hide…
robotkitteh 