Written by Koji Suzuki.
Kensuke Suehiro is a washed-up drop-out who is best friends with his successful peer, Toshihiro Aso. During an evening of drinking and debate, Kensuke learns his friend has left a female companion alone in the car. She is Yukari Nakazawa, a meek member of a local religious cult who drags after Toshihiro despite his frequent verbal abuse. Kensuke is shocked by his friend's repulsive behavior, and even more so when, a couple months later, Toshihiro tells him the tale of how he abandoned Yukari on a small artificial island in Tokyo Bay. Kensuke is uncertain about the event's validity but, before he can learn more, Toshihiro catches a rare cancer and quickly dies.
Nine years later... hang up a second. It's been nine fucking years and Kensuke hasn't once called the police? Sure, it might be nothing more than a brash break-up lie, but the possibility of its truth has haunted Kensuke all this time, so why hasn't he done a damn thing about it? Heck, you don't want to alert the authorities, then do what Toshihiro did and sneak out to the island at night to see for yourself! Suzuki's asking me to suspend my disbelief a bit more than I'm willing with this one.
Anyway, nine years later, a former colleague invites Kensuke to join him for an on-site survey of that very same island. And what they discover is... a spoiler that doesn't really need to be spoiled in this review.
It's an interesting tale, but the fact that it entirely hinges upon Kensuke's aforementioned inability to alert authorities pretty much kills it.
Another strike against the story is Yukari's cult. There's no development, almost no reason for it to be there other than setting up the idea of a solitary paradise that's eventually used against her. And there's an added twist to this belief on the last page that I didn't entirely buy.
In the end, it's still a decent story. If you like Suzuki, go ahead and give it a go. None of the logic issue are any worse than some he's used in the past. If you hate Suzuki, it's more of the same.