Hagi: Castle Town Forged by Magma - Japanology Plus

Key Concepts

• Abu Volcanic Group: A collection of 56 small, individual volcanoes in Hagi that shaped the region's geography.
• Kasayama: A 112-meter-high volcano that serves as a primary example of Hagi’s unique volcanic history.
• Hagi-yaki (Hagi-wear): Traditional pottery known for its porous clay, "crackle glaze" (kannyu), and the "seven transformations" (color changes over time).
• Natsumikan: A citrus fruit that thrives in Hagi’s mineral-rich, well-draining volcanic soil.
• Climbing Kiln (Noborigama): A traditional multi-chambered kiln built on a slope, designed for high-temperature wood firing.

1. Geological Foundations

Hagi’s landscape is defined by the Abu Volcanic Group, which formed approximately 1 million years ago. Unlike typical stratovolcanoes, the volcanoes in this region are characterized by single-event eruptions. Magma finds a path to the surface, erupts once, and then the channel cools and solidifies. Subsequent eruptions occur at different locations, resulting in a landscape dotted with small, flat-topped volcanic features rather than a single massive mountain.

• Kasayama: A 10,000-year-old volcano. Its crater is accessible to visitors, which is rare in Japan due to the safety risks associated with most active volcanoes.
• Soil Composition: The volcanic ash creates highly fertile, well-draining soil, which is essential for the local agricultural success of natsumikan.

2. The Integration of Volcanic Resources into Culture

The town of Hagi has historically utilized its volcanic environment for infrastructure and industry:

• Architecture: During the Edo period, the castle town was built on a delta formed by volcanic sediment. Because the area lacked traditional stone, residents used black volcanic rock (hardened magma) to construct castle walls and town foundations.
• Marine Ecosystems: Jagged lava rocks extend into the Sea of Japan, creating habitats for seaweed, which in turn supports a rich variety of marine life, including turban shells, abalone, and sea urchins.
• Myojin-ike Pond: A unique saltwater pond connected to the sea via underground channels. It serves as a sanctuary for saltwater fish (such as pufferfish and rays) that are often offered to the local shrine by fishermen.

3. Hagi-yaki (Pottery) Methodology

Hagi-wear is a 400-year-old craft deeply tied to the local geology.

• Raw Materials: The clay is sourced from volcanic deposits (specifically Daido and Mishima clays).
• The "Seven Transformations": A defining characteristic of Hagi-wear is its ability to absorb tea over time, causing the "crackle glaze" to change color, typically darkening to a rich, aged tone.
• Firing Process: Traditional kilns use koyamatsu (pine wood rich in resin) to reach high temperatures. The process requires constant manual labor, with teams rotating to stoke the fire continuously.
• Modern Evolution: While traditional tea ceremony utensils remain central, modern potters are experimenting with gas kilns and new glazes to create contemporary art, ensuring the craft remains relevant to younger generations and international apprentices.

4. Agricultural Significance: Natsumikan

The natsumikan (summer orange) is a symbol of Hagi.

• Cultivation: The mineral-rich volcanic soil and abundant sunlight provide ideal conditions for the fruit.
• Culinary Application: The fruit is used in traditional confections where the entire rind is blanched repeatedly to remove bitterness. A seasonal delicacy, giddi, is made from unripe green natsumikan by slicing the peel and simmering it in syrup.

5. Synthesis and Conclusion

Hagi serves as a prime example of how geological history dictates human development. From the volcanic rock that physically supports the town’s historic walls to the clay that defines its world-renowned pottery and the soil that nurtures its iconic citrus, the town’s identity is inseparable from its volcanic origins. As Peter Barakan notes, Hagi’s charm lies in its quiet preservation of these traditions, where the "hidden charms" of the town are all fundamentally linked to the volcanic activity that shaped the region 1 million years ago.