About 5km northeast of the town is this 112m dormant volcano. The top has gorgeous views of the Sea of Japan and a tiny 30m-deep crater. There is also a walking track around the coast. From late February to late March a beautiful grove of camellias blooms here.
The pond at the mountain's base, Myōjin-ike (明神池), is connected to the sea and shelters a variety of saltwater fish. Look and listen for birdlife in the surrounding trees.
About a five-minute walk up the mountain from the pond is Hagi Glass, where quartz basalt from the volcano is used to make extremely tough Hagi glassware. The showroom and shop display beautiful coloured vases and you can watch the glass-blowing process. Next door is Hagi's own beer and citrus-juice factory, Yuzuya Honten. Stop in here to see the very small team at work, taste juice in the attached shop, or have a refreshing mikan-flavoured (satsuma) soft cream.
Buses go to Kasa-yama from Higashi-Hagi Station once every one to 1½ hours (¥280, 15 minutes); get off at the Koshi-ga-hama stop, about eight minutes' walk from the base of the mountain and Myōjin-ike.