This is par for the course in Kyushu
This volcano is located in a large complex of volcanoes in central Kyushu. There are often several active volcanoes in the complex.
The city of Kagoshima (approx 750K people IIRC), in southern Kyushu, is located about 10 Km from Sakura-jima volcano, which is active. I've been there, you can rent bicycles in the city, take a fery to the volcano, and ride around it's periphery along the shoreline. It is an interesting 40 Km ride I must say, especially downwind of the cinder cones: the air is full of SO2 and ash falls like a winter blizzard.
It *looks* like another huge blow to the country, but this kind of volcanic eruption happens all the time in Japan, and nobody gets terribly exercised about them.
The real problem is in the tsunami zone, this volcano is a mosquito bite.