Ksitigarbha's vow is the most extreme in the tradition: he will not become a buddha until the hells are empty, and the hells are not going to be empty. In China he presides over the dead and the underworld courts; in Japan, as Jizo, he became the protector of children who died young, of stillbirths and miscarriages and abortions — the small stone figures in red bibs and knitted caps at temples and roadsides are left by parents, sometimes decades after. It is one of the few places in Buddhism where an entire devotional practice grew up around grief with no doctrinal argument attached, and the tradition simply made room for it.