- Located in Nagasaki prefecture in the southern part of the Shimabara peninsula.
- Hara castle was another of the castles belonging to the Arima clan (in addition to Hinoe castle). It was the largest-scale castles to be built within what is now Nagasaki prefecture.
- The stone wall fortification technique that was used in Hara castle’s construction is characteristic of castles built around the time of Oda Nobunaga and Toyotomi Hideyoshi.
- Once the Matsukura clan had taken over the Arima clan’s domain, Christians began to suffer torture in the “jigoku” at Unzen (“jigoku” literally means “hell” and in this context refers to hot springs of extremely high temperatures). These tortures were performed with the intention of forcing Christians to renounce their faith. Many refused to do so, however, and were martyred.
- In 1637, at the time of the Amakusa-Shimabara rebellion, rebel forces barricaded themselves in Hara castle.
- After the rebellion, Christians were wiped out. However, many people migrated to the area from elsewhere, and worked hard to revive it.