Kameiwa Cave

Published: Aug 11, 2026

Updated: Aug 11, 2026

Kameiwa CaveNomizo FallsKimitsuheart-shaped lightEdo diversion

Representative image — not a photograph of this location.

A small waterfall drops through a hole cut in rock in a wooded valley in Kimitsu, and for a couple of weeks twice a year the sun rises at exactly the right angle to shine through the opening. The light beam and its reflection in the pool below form a shape that reads as a heart, which is why a quiet forest stream in inland Chiba became, briefly, one of the most photographed places in Japan.

The hole is not natural. It was cut in the Edo period as a tunnel to divert the river and open up new rice paddies — a technique called kawamage that was used across the Boso peninsula — and the waterfall is what happens where the diversion drops. Locally it gets called Nomizo Falls, though strictly that is the fall downstream. The rest of the year the valley is simply a mossy stream with a boardwalk, which is a fine thing to have twenty minutes off the Aqua-Line.

Essential Information

Opening Hours

Open access | The light effect requires sunrise to mid-morning

Closed: Open year-round

Entrance Fee

Free | Free parking for around 125 cars

Best Season

March–early April and September–early October at dawn for the heart-shaped light | Fresh green in May

Visit Duration

45–60 minutes

Getting There

Access Information

Sasa, Kimitsu, at the Shimizu Keiryu Hiroba. Car recommended — from the Aqua-Line take Kimitsu IC and the Boso Skyline toward Kamogawa on Prefectural Route 24. By train, take the JR Kururi Line to Kazusa-Kameyama Station then a pre-booked demand taxi, about 15 minutes. Free, with three free car parks holding around 125 cars in total; the first fills at weekends. The light effect appears from sunrise to mid-morning in roughly March to early April and September to early October.

Insider Guide

Premium

**The heart only appears twice a year, at dawn.** Roughly March to early April and September to early October, from sunrise through the morning, when the sun angles into the right-hand side of the cave. At any other time or hour it is a waterfall in a hole. **Those windows coincide with the equinox weeks.** Around the spring and autumn higan periods is the specific advice locals give, and it means arriving before sunrise and in the dark. **Three car parks, and the nearest fills.** The first lot has 26 spaces and goes early at weekends. The third, with about 80, is a longer walk but reliable. **Do not walk in the stream.** The moss on the rocks is the reason the valley photographs the way it does and it is fragile. Boardwalks are provided. **Public transport barely works.** The Kururi Line plus a demand-responsive taxi that must be booked in advance. This is a car destination.

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