This is a great blog: https://www.thewanderingsuitcase.com
And here is the page about Naoshima: https://www.thewanderingsuitcase.com/naoshima-island/
MG, the intrepid author of The Wandering Suitcase, takes us on a very good tour of Naoshima. Her recommendation to rent a bicycle is sage advice, and may save you some time as you have to hustle back to the port and catch the last ferry back to Takamatsu!
Naoshima is rich with art, nature, fun things to see and do, restaurants, and a coastline that can’t be beat. Only about an hour and fifteen minutes by ferry, it is a must visit when you come to Kagawa!