Japan being such a mountainous country, there are bound to be prefectures with a famous mountain as its main symbol. Mt. Fuji for Shizuoka, Mt. Aso for Kumamoto, and for Kagoshima, it’s definitely Sakurajima.
Two reasons why most people in Japan know Sakurajima: 1. It erupts fairly often and makes national headlines, especially when the dark ash covers city streets, cars, laundry, etc. 2. When you visit the city of Kagoshima, Sakurajima is the dominant natural feature visible everywhere you go (lower photo, as seen from Shiroyama Park).
Sakurajima just recently erupted on April 25, 2021. An explosive eruption expelled a pyroclastic flow for 1.8 km. Nothing major though, with no damage nor casualties. Nearby residents (living as near as 2.5 km away) did not need to evacuate, but they were put on alert. Can’t imagine living that close to a volcano.
During the past few decades, Sakurajima has been erupting from two craters near the summit. In Nov. 1986, an eruption threw a five-ton rock (2m diameter) for three kilometers. The rock hit a ferroconcrete single-story hotel and pierced the roof and went all the way down to the basement. It made a 3-meter wide hole in the building. Six hotel guests and staff were injured. Scary. Falling meteorites are enough to worry about, but volcanic rocks too. Land prices must be cheap around Sakurajima. 
Kyushu actually has the most active volcanoes in Japan. Mt. Aso in Kumamoto is still active. And Unzen erupted in the early 1990s. If you like volcanoes, go to Kyushu.
As its name implies, Sakurajima was an island, but it’s now a peninsula in Kagoshima Bay after major lava flows in 1914 connected it to Kyushu. Sakurajima is part of Kirishima-Kinkowan National Park.
When it’s not erupting, it’s possible to visit Sakurajima. A short ferry ride from Kagoshima Port to Sakurajima. We couldn’t hike up to the summit or craters, but there are walking paths at the foot and slope of the mountain. It was close enough (upper photo).
Another thing that struck me about Kagoshima was the local dialect. Totally couldn’t understand it. I was amazed at the diversity of the Japanese language and dialects. 
The main train station is Kagoshima Chuo Station. JR Kyushu Shinkansen stops here. There is also Kagoshima Airport.