Square Enix have updated their e-STORE with a set of 20 different official Kingdom Hearts novels, all in Japanese. The set is available now and costs ¥14,450 (approximately US$185.45). The full list of novels included can be seen below. Thanks to bKvEBVAvUq for the tip.

Kingdom Hearts Vol.1 & Vol.2

Kingdom Hearts: Chain of Memories Vol.1 & Vol.2

Kingdom Hearts: Chain of Memories Vol.3 "Reverse / Rebirth" Riku

Kingdom Hearts II Vol.1 & Vol.2 & Vol.3 & Vol.4

Kingdom Hearts II Short Stories Vol.1 & Vol.2

Kingdom Hearts 358/2 Days Vol.1 & Vol.2 & Vol.3

Kingdom Hearts Birth by Sleep Vol.1 & Vol.2 & Vol.3

Kingdom Hearts Re:coded

Kingdom Hearts 3D [Dream Drop Distance] Side Sora

Kingdom Hearts 3D [Dream Drop Distance] Side Riku