The observation deck is very close to the parking lot, so you don't need a flashlight.

To get there, just drive up the mountain. If you're a first timer, it's best to go in the evening and wait for the night view, as the route is easier to follow and you can enjoy both the night view and the sunset. The route from the north is also relatively safer.

[Useful points of concern]
If you're coming from Kure City, the route on the south side is steep and narrow, so the route from the north side around the west is wider and relatively safer. It's a longer route, but the roads are well maintained, so the time is almost the same.
There is a simple toilet at the observation deck parking lot, but it's not very good, so it's probably best to go and use it before you visit. However, the toilets at Haigamine Park, which is a little further away, are relatively clean.