This unique type of door, called nijiriguchi (which is translated as "crawling-in entrance") requires a good flexibility and if you're visiting a chashitsu for the first time and associating it with the traditional restaurants, you may be tempted to think that this is a service door for the host performing the ceremony. But that's not true... the host is using the regular door, bringing in the tools for the ceremony.
The nijiriguchi is to be used by... the guests. And entering the tea room while bending like this, is a symbol that inside, during the tea ceremony, all guests are equal, regardless of their social status...
Due to my size, I have no problems using a nijiriguchi... but I witnessed some fellow Western travelers struggling to get inside, so here's how you should use it: first, bend down and place your hands and your head inside. Then, get inside one knee and slowly slide sideways...
EXIF info:
Nikon D90
Lens: 8-16mm F/4.5-5.6G
Focal Length: 8mm
Aperture: F/5.6
Shutter Speed: 1/200s
ISO Sensitivity: ISO 200