An exercise in space management or one of desperation? It looks as though entering both the car and the building will prove challenging, to say nothing of parking.
For those doubting the authenticity of such a dwelling, be assured that they do exist, and it is far from uncommon to see garage doors which close only halfway, with a car bonnet protruding into the street. Presumably access is only by the rear of the vehicle?
And yes, these inherently silly buildings do enjoy a low reputation even amongst the Japanese.
The high cost of idling land in central Tokyo seems to preclude leaving such spots vacant until they can be consolidated with a neighbouring plot, and even with the high rate of rebuilding, it seems two plots coming onto the market close enough to merged into a more viable area is not a common enough event.
Still, it is at least innovative architecture?