The crying dam and mannequin pis, Akasakazawa Dam, in the woods of the Kosugi area of Ogose hiking Town, Saitama Prefecture.
The crying dam
The Akasakazawa Dam is a dam of the Akasaka river, a tributary of the larger Mugihara river. It is nicknamed (and better known as) the crying dam, because it can appear like the dam is crying. There are three semicircular holes in the dam to let water out gradually. They look like the eyes and mouth of a face. Whether that was intentional or not I do not know.

Mannequin Pis
What I do know was intentional was the erecting of a mannequin pis in front of the dam. Along with a monkey swinging from the fake tree on which the mannequin pis stands. Both were erected 30 years ago, in 1990, as a way to create interest in SABO work. Sabo is a type of sediment control founded in Japan. The crying dam is a Sabo Dam, built to control water flow, erosion and sediment shift in the area.

Sabo Work
SABO is a Japanese term that means erosion and sediment control works. The Japanese style of SABO erosion control works is more intensive than Western erosion control works. The term SABO is known internationally, and is used both in and outside Japan.
Source: Sediment hazards and SABO works in Japan, Takahisa MIZUYAMA

The crying dam, mannequin pis and swinging monkey are not worth going out of your way to visit as an attraction, because you wouldn’t spend long at the location. However, the area, like much of Ogose, is a nice area to hike in. The dam is 800 meters from the entry point off Hydrangea road. There is a steady uphill slant. The road is flanked by beautiful trees and the Akasaka river.

Please note there are no facilities at the crying dam, there isn’t even anywhere to sit. The nearest toilets are about 1.3 kilometres away, on the hydrangea road. There are also no vending machines in the area.
Access
You can drive up as well. The road is too narrow for a wide truck, but there is ample room for up to a seven seater car. However, if you did meet another vehicle on the way, one of you would have to reverse to a spot where you can pull in. There are only three places along the road that there is enough room to pull in.

Beside the dam there is enough room for two cars to park bumper to bumper. There is also enough space to do a u-turn. There is little risk of a traffic jam as the spot is quite off the beaten track and rarely visited.
If you are coming by public transport, be prepared for quite a bit of walking. According to Hauyashi blog it takes an hour and forty minutes to walk from Ogose Station. Ogose station is on both the JR Hachiko line and the private Tobu Ogose line.
Japan has so many amazing places! This one… just amazing, fairy tale like!