I saw one in Japanese for the "first class cabins" -- essentially, the "cabins" are separated from each other by partitions that are not fully ceiling-to-floor height, and from the corridor by a thin curtain. As a result the reviewer barely got any sleep due to footfalls, conversations, etc.

I would just as soon stay at one of the business hotels near Anamori Inari Station for a little bit more and use their free shuttle bus to HND.