In the early Meiji era, against civil unrest and the end of the samurai
way of life, Japan's crime rate skyrocketed. As prisons overflow, the
government has no choice but to build a new, inescapable prison. This
prison is Gokumonjo, located in the center of Lake Biwa, which means it
relies on the three sons of the Kumo family to transport criminals to
it. But is Gokumonjo truly just a prison for petty criminals?
A dreaded murderer intrudes on the Kumo family's peace and brings with
him news of an ancient calamity: Orochi. As Soramaru realizes his elder
brother Tenka has been hiding things from him, he begins to look to
outside sources to help him become stronger. At the same time, still
other outside forces begin to reach out to Tenka for his knowledge of
this ancient evil. The race to find and control Orochi's vessel begins!