Hi nitta, lurch was correct, but 's
does not always mean "is" like he said.
Most of the times it is a possessive (as correctly explained by our friend TCD!), so "Ken's Apple" does actually "the Apple which is Ken's property".
By the way, excellent title - the fact that the main character is an onanist reminds me of a (kinda famous) doujinshi, Onanimaster Kurosawa