Kozagawa Monolith: Japan’s largest bedrock and legendary story│Wakayama Japan

The Kozagawa Monolith, located in Kozagawa-cho, Wakayama Prefecture, is a place where the wonders and mysteries of the natural world coexist.

It is proudly designated as a nationally designated natural monument, and its gigantic bedrock is said to be one of the largest in Japan, attracting the fascination of many people.

Its characteristic stone quality, historical background, and legendary stories further enhance the charm of this rock.

In this article, let’s dig deeper into the Kozagawa monolith and explore its mysterious world.


Overview and characteristics of the Kozagawa monolith

The Kozagawa Monolith, located along National Route 371 (Prefectural Route 38) in Kozagawa Town, Wakayama Prefecture, is a miracle of nature known as a nationally designated natural monument.

This rock is approximately 150 meters high and approximately 800 meters wide, making it one of the largest single pieces of rock in Japan.

The stone is made of rhyolitic tuff called the Kozagawa arc-shaped dyke, and because it is homogeneous and hardened, it has endured weathering and erosion and has continued to exist for centuries.

This natural giant rock was designated as a national natural monument in 1941, which is understandable given its rarity.

Generally speaking, no matter the geology, it is rare for large rock bodies to survive due to faults or weathering, but the Kozagawa monolith is an exception.

Rock ecosystem and Helitori moss

An interesting fact about this monolith of the Koza River is the existence of a lichen called Heritrigoke that lives on this rock.

A detailed survey in 2001 confirmed that this rock is home to the world’s largest and longest-lived Helitori moss.

Its size and lifespan are unparalleled, and it is the subject of scientific research and investigation.

Legend and Yin-Yang Falls

The Kozagawa monolith is not only home to beautiful scenery, but also legends.

A long time ago, a monster appeared that loved the rocks of Taiji, and began devouring the rocks in the Koza River basin one after another.

However, when the monster reached the monolith, it was chased by Kurado’s dog, and the legend has passed down that the monster ran away because the dog didn’t like it.

According to this legend, the vertical depression in the center of the monolith is said to be the shape of a monster’s teeth, and when it rains continuously and water overflows from the upper pond, the “Yin-Yang Falls” appears.

It is said that these are the tears of a demon’s frustration.

A mysterious story lives in the monolith of the Kozagawa River.

Roadside Station Monolith

We offer activities such as canoeing and tubing, sauna, day camp, and BBQ.

For more information, please see the official roadside station monolith website (external website).

 290-2 Aise, Kozagawa-cho, Higashimuro-gun, Wakayama Prefecture
Telephone number
■Business hours
・Summer (March to November)
 Weekdays 09:30-17:00 Saturdays,
 Sundays, and holidays 8:30-17:00
・Winter season (December to February)
 Weekdays 10:00-17:00 Saturdays,
 Sundays, and holidays 8:30-17:00

Basic information about “Kozagawa monolith”

InfoMonolith of Kozagawa River
 Aise, Kozagawa-machi, Higashimuro-gun,
 Wakayama Prefecture
Parking lot
 Yes (Roadside Station Monolith)

Restaurant search/reservation

Have a great trip with delicious food!

Surrounding touring spots

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