I don’t know. I have a box of mixed up parts. A few of them have this marking on them. Just hopeful someone recognizes it…Do you know what make of bike it's off ?
Then you could check what brands of electrics they use, and then search those component manufacturers for their branding..
that marking is Suzuki. The part i have is aOk. I see. I've seen that symbol before. I'd take it to be AD, which makes me think Denso, but I looked at their branding and all their d's are always D. No sign of any AD either though it could stand for American or asian Denso.. Best guess I can come up with..
I did see that Denso supply to Polaris.. so if you think they are polaris it might be right.. Then.. Denso probably supply to heaps of jap makers too.. haha.
Good luck with that.