The Japanese keelback (Hebius vibakari), sometimes called the ringed snake or water snake, is a species of colubrid snake, which is endemic to Asia. It was first described in 1826 by Heinrich Boie as Tropidonotus vibakari.

It is found in northeastern China, Japan (Honshu, Kyushu, Shikoku), Korea, and Russia (Amur Oblast, Khabarovsk Krai, Primorsky Krai).

It is a small snake, growing to a maximum total length of 44 cm (17+1⁄4 in), with a tail 10 cm (3+7⁄8 in) long.^{[citation needed]}

Dorsally it is olive or reddish brown, with small blackish spots. Some specimens may have a dark olive or blackish vertebral stripe. The upper labials are yellow, with black sutures. On each side of the nape of the neck there is a yellow dark-edged diagonal streak, these two streaks converging posteriorly. Ventrally it is yellow, with a series of brown dots or short lines at the outer ends of the ventral scales.^{[citation needed]}

Dorsal scales strongly keeled (except outer row), arranged in 19 rows at midbody. Ventrals 127–151; anal plate divided; subcaudals divided 59–79.