The site's popularity has been attributed to the 1960 novel Kuroi Jukai (Black Sea of Trees) by Seichō Matsumoto.
It depicts the enacted vengeance of a jilted covergirl who supernaturally transforms into a demonic spirit when she kills herself in the famed suicide forest of Aokigahara Jukai, Japan, enabling herself to wreak a violent revenge, one by one, upon those who helped her ex-boyfriend leave her.
another name for Aokigahara, the forest around Mt. Fuji in Japan, sometimes simply called "jukai," ("Sea of Trees")
In place names, it is generally a conjunction, and hence pronounced ga, particularly as 「～ヶ原」 (-ga-hara) "field of ...", as in 青木ヶ原 (Aokigahara, laurel-'s-field, field of laurel).