Naoshima – What are the must see attractions?

Hi, I am trying to plan a schedule for day trip to Naoshima (from Okayama) in late March.
I cannot ride a bike and therefore have to relay on the buses/shuttles.
It seems to me that it is impossible to see everything there is to see on the island in 1 day so I am trying to prioritize.
What are the best/must-see attractions on the island? how much time should I allocate to each of them?

Thanks