Based heavily on Japanese culture (as opposed to the usually Western influenced planes), the plane is the setting of the entire Kamigawa Block. (The Champions, Betrayers, and Saviors of Kamigawa expansions.)
Kamigawa is divided into two areas, a material world (the utsushiyo 現し世) and a spiritual world (the kakuriyo. 隠り世). The creatures of the utsushiyo are Kamigawa's humans, Kitsune, Soratami, Nezumi, Ogres, the Akki, and the Orochi.
Making up the kakuriyo are the Kami, who, as spirits embodying concepts, are widely diverse. The corrupted Kami who embody suffering and wickedness are called Oni, (who are worshipped by the ogres). However, the five greatest spirits who reflect the five colors of mana are known as the Myojin, who are only surpassed by the eight-headed serpent O-Kagachi.
The Kamigawa Block takes place during the Kami War, between the utsushiyo and kakuriyo. The war began when Konda, Lord of Eiganjo, stole the scion of O-Kagachi. In retaliation the kami attacked the inhabitants of the plane in an effort to reclaim That Which Was Taken. Since spirits could be defeated in battle but still return for future conflicts, it was already a losing battle for the mortals once the war began.
The war ended when Michiko Konda, with the aid of Toshiro Umezawa and others, managed to free the scion (which took the name Kyodai), and defeated both O-Kagachi and Konda.
On Kamigawa, denizens of the plane waged a brutal war against their own gods.
This plane, reminiscent of sengoku-era Japan, contains two symbiotic worlds. One is the utsushiyo, the material realm of mortals, and the other is the kakuriyo, the realm of the kami. For many hundreds of years, Kamigawa's denizens peacefully worshipped the spirits inherent in everything—spirits of sacred places, objects, and ideas.
Each of these kami was a divinity, and the way to happiness was to honor the kami and live by their ways. The inhabitants of Kamigawa were content with this life of devotion. Then the unimaginable happened: their gods turned on them.
Slowly at first, kami began to take form in the material world. Some scholars believed the kami were delivering a message or a warning. But their appearance was so alien, so surreal, that no meaning could be discerned.
At that time, the plane's most powerful warlord, the daimyo Takeshi Konda, ruled over the Towabara Plains from his stronghold at Eiganjo. But even as his armies and samurai secured more territory in Konda's name, the kami manifested in ever-greater numbers.
Then came a night that changed Kamigawa forever. A few miles from Eiganjo Castle, the kami set upon the town of Reito. Scores of spirit-world monstrosities swept through the town, killing nearly every living thing. Hundreds were slain; few survived. The Kami War had begun.
Over the next twenty years, spirits of every shape and size would descend on the plains, ravage everything in their path, then inexplicably stop just short of Eiganjo. Throughout this spirit-world siege, Konda remained within his stronghold, mysteriously safe from harm.
Kamigawa's people were left to wonder why the kami betrayed them even as they fought for survival. What had they done wrong? How could they discover why the kami were so angry? And what happens when a world must kill its own gods to survive?
In truth, it was the proud daimyo Konda who began the war. With aid from moonfolk allies, Konda kidnapped a kami to secure his own power and immortality. This outraged the great O-Kagachi, the kami of all things. Its ire began a struggle that would take countless lives.
It was the self-serving machinations of the ochimusha named Toshiro Umezawa, ironically, that set the stage for the end of the Kami War. Only the intervention of Konda's daughter Michiko as well as the stolen kami itself, an entity that came to call herself Kyodai, could placate the kami and restore a fragile peace to the land of Kamigawa.