Looks like you went almost exactly a month later than I did. It was completely overgrown in October, but I could tell that there was once a path down the right with how the shrubbery was growing in.
Maybe someone cleaned it up? I'll have to revisit as I didn't do all I wanted on Ikei Island that day anyway.
The first tunnel had construction going on and the tunnel was why I originally went as I wanted the bridge from the seawall far out in the water to its right. I never used that shot because 105mm filled the frame end to end with the bridge, but it just looked so insignificant with the height of the cliffs on Miyagi Island and Ikei Island. The oil pump in the background was ugly too.
There was construction when I went also for this photo. I really enjoyed Ikei beach, it has some very nice sand and a peaceful vibe! You can also get on the roof of the main building. Across the street from the beach there is a hidden path near the boat ramp, I walked in a little bit it was mostly overgrown so I did not finish. I wonder what is at the end of that path!