The Kumamoto Castle Loop bus, Shiromegurin, starts from Kumamoto JR station and then heads to the castle where it does a loop around the extensive grounds before heading downtown and then back to the station.
Many of the most popular tourist sites in the central area are reachable by it. It stops at the Kotsu bus station, Kumamoto Castle parking area, the Children's Culture Center, the Prefectural Art Museum, the Municipal Museum, Hosokawa Residence, Traditional Crafts Center, and the Art Museum Chibajo Annex. Downtown it stops near the Contemporary Art Museum and Lafcadio Hearn House.
A single ride is 130 yen for adults and 70 yen for children. A one day pass is 300 yen and 150 yen.
If you plan on going further afield there is a new city-wide public transport pass at 500 yen for one day or 800 yen for 2 days.
The 2 days do not have to be consecutive. This pass covers all the trams in Kumamoto as well as all the city buses including the Shiromegurin and also JR trains within the prescribed area.
The Kumamoto Port Shuttle Bus in not included in the pass, though if you take a regular bus to the port the pass covers part of the fare.
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