The Sanzu-no-Kawa (三途の川, lit. "River of Three Crossings", or the "Sanzu River") is a mythological river in Japanese Buddhist tradition similar to the Chinese concept of Huang Quan (Yellow Springs), Indian concept of the Vaitarani and Greek concept of the Styx.
Before reaching the afterlife, the souls of the deceased must cross the river by one of three crossing points: a bridge, a ford, or a stretch of deep, snake-infested waters. The weight of one's offenses while alive determines which path an individual must take. It is believed that a toll of six mon must be paid before a soul can cross the river, a belief reflected in Japanese funerals when the necessary fee is placed in the casket with the dead.
The Sanzu River is popularly believed to be in Mount Osore, a suitably desolate and remote part of Aomori Prefecture in northern Japan.
Similarly to the Sanzu-no-Kawa, there is also the Sai no Kawara (賽の河原, lit. "Riverbed of Death"), a boundary by which the souls of children who died too early cross over to the realm of the Dead, with the help of Jizō, a Kami/Bodhisattva who helps the souls of children who died too early to avoid the attentions of the Oni and of Shozuka-no-Baba and Datsueba.