Vermilion Souls (2007)

Set in Tokyo seven years after the end of WWII, this surreal story revolves around the dreams and realities of a young boy who strays into a strange mansion while out chasing fliers dropped by a small aeroplane. Confined inside are four adults suffering from an incurable disease ('porphyria', which the author avoids specifying by name in the screenplay) which prevents them from having exposure to the sun.