Yes, Kokura Castle is highly accessible via the Sanyo Shinkansen bullet train network. From Fukuoka, the journey takes about 15 minutes, while Osaka is approximately 2.5 hours away by shinkansen. Once you arrive at Kokura Station, the castle is just a 15-minute walk, or you can take a shorter 10-minute walk from Nishi-Kokura Station on the local Kagoshima Main Line.