Summary: Proper manners dictate height and depth when bowing and clinking glasses
Respect and hierarchy are paramount in Japanese society. In general, one should always show respect to one’s elders and superiors. This is demonstrated, for example, in toasting and and bowing.
Whenever people bow, which is often in Japan, it is proper for the “underling” to bow deeper to his or her superior. As a side note, if space is limited, bow to one side of the other person to prevent conking heads.
Similarly, when glasses are clinked, you should always click with your rim lower than that of your superior (elder, boss, etc.). When several people are clinking glasses together, you can observe this awareness of respect and hierarchy.
It is also good form never to fill your own cup. People should keep an eye on their companions’ cups and always refill theirs. Yours should be filled and refilled by someone else.
If you travel to Japan, people will notice and be impressed if you observe these simple customs of respect.
Some fun can be had with these customs. For example, if you are the boss or the respected elder, when several glasses are about to clink, you can suddenly lower your glass and enjoy the sight of everyone else having to hurriedly lower theirs as well before contact. This usually elicits laughter.
Mom had some fun in a similar way when we were visiting Keishoji. As honored visitors from overseas, we were shown great respect and gratitude everywhere we met. Being the eldest meant Mom typically occupied the position of highest respect in nearly any gathering we attended.
One evening, about a dozen of us were seated for dinner. As was customary, we sat on the floor next to a low table. The priest’s brother, a fisherman, had to leave early because he needed to rise very early the next morning to fish.
We were all seated on the floor, and upon taking his departure, the fisherman dutifully nodded and bowed his head to each of us. Turning to my mom, the most respected person in the party, he bowed low. Mom bowed low in return, which obligated him to bow lower.
Mom kept bowing lower and lower, and he kept responding until his body was basically plastered to the floor. He finally protested that he could bow no further. Everyone knew Mom was having a little fun with him and we all had a good laugh.
As for myself, I hope I am still agile enough to sit on the floor and bow low when I reach my 70s and 80s.