Rank is too ingrained in the budo to claim that it doesnt exist. Even when there are no tests and formal rank certificates of any description given out, there is rank.
We recognize those who know more than us, those who are older, those who have been around longer. This is all taken into account in the concept of sempai and kohei, senior and junior. Sometimes it’s called the “Japanese apprentice” system and one of my favourite stories is about a fisherman who, for 15 years, hoped and prayed that one of the other guys would fall overboard or quit. That way a new guy would be hired and it would be his job to clean the toilets.
In the west we usually assume sempai is anyone who joined the dojo ahead of us, or anyone who got the rank first. Now right there you can get a contradiction since a senior in time served might just slip behind a newer guy in rank. Then what do you do? Depends on the dojo of course but as that higher ranked junior-time guy I’d sit exactly where I always sat, downwind of the other guy, until invited or told to move.
What happens when someone joins before you but is absent for huge chunks of time or moves and comes back? First in is first in. If they ever sat higher than you, it’s good for you to consider that they always sit higher than you. I’m now older than my father and my grandfather ever were, they’re still my ancestors even if I became more ancient than they.
Chronological age can make a difference to who’s sempai, if you come into the dojo at roughly the same time, or even further apart than that, an older man would likely be sitting upwind of a younger by virtue of the respect due to age and life experience. In other words if you would offer a seat on the bus you should likely offer the higher seat in the dojo. It would be only the most strict of dojo that would not tend to push a major businessman or politician up the seating ladder, and it would be up to them to resist that push. The higher your status outside the dojo, the more careful of dojo heirarchy you should be inside. The president of the company might sit pretty low down in the company dojo (but that might not mean his employees beat the tar out of him on days other than his birthday).
Sempai can be a rather formal position in many western dojo, with students taught to call the highest student(s) by that title, and that’s fine, but as a general rule, if they got there first, outrank you, are older than you, or are someone you’d call “sensei” on the street (doctors, lawyers, professors and such) you should consider them your sempai.
Take into account other ranks as well, in the CKF we have 7 and 8dan kendo sensei who have started iaido and are grading at very junior dan ranks. I strongly suspect most of our higher ranked iaido folks call them “sensei” no matter where they choose to sit during class. I certainly do. Same with some very highly ranked folks from outside the organization. If I’m teaching they sit below me on the mat of course, but they certainly are not addressed as “dave” or “fred”. Although I was technically the second 7dan in the country, I consider myself the fourth ranked. The two I consider ahead of me are an 8dan kendo sensei and a direct iaido teacher of mine, both of them with many more years practice in than me. When you are given a rank has nothing to do with seniority in cases like that.
Actually, unless there is a formal “rank” of sempai, you would address people above you either formally or as sensei, and those below you politely or as sensei. Sensei? Yes, if someone below you in the dojo or elsewhere is a teacher, they get to be called teacher. Hey, I sometimes get addressed as Taylor Teacher by the visiting Japanese sensei so consider that when next you are wondering what to call someone. I figure “Taylor Teacher” is a bit more respectful even than “Taylor Sensei” because they’ve taken the bother to translate it.
I’m sitting here trying to think of other informal rank structures but I think sempai – kohei is pretty much it. It’s a sorting out of seating arrangement (or not, in my dojo I prefer seniors to mix between the juniors for instructional reasons) that goes on without much prompting from sensei.
Now, that doesn’t mean there are not other ways of ranking, a name board in the dojo for instance will tend to formalize the informal, as will a list of names on the organization website or a demonstration programme. Of course you have to know how to read those, the website will likely be read top down and a demonstration tends to close with the most senior person, the juniors all demonstrating first in sometimes esoteric ranking calculations.
Sensei may designate specific teaching assistants based on skill rather than on time in or rank if such exists. If the assistant comes from the class and is junior to many of the other students, he would be well advised to sit where he usually sits rather than moving himself upwind. If sensei wants him recognized a bit more formally than just appearing up front to help in a kata, he may actually pull the assistant over to the teaching side of the dojo rather than putting him up the student ladder. Yes it can be that complicated, watch the natural sorting out of position that goes on up front at a big seminar. Glances up and down the line, palms offering a place up and heads shaking off the offer all over the place. Notice especially how comfortable and polite the arranging is. If there are resentful looks at being bumped down the line you may want to pay attention to what’s happening in your organization, there could be trouble. My advice, take a modest place and resist only mildly if told to move up. It is as tacky to insist on the lower position as it is to insist on a higher.
All this sorting is a measure of mutual respect, not a contest and certainly not a prize to be sought. Pride or prideful-humility has no place in matters of respect in the dojo.