Originally Posted by
Jeff Wills
I would like to see the rest of the crank but I suspect it’s a Shimano FFS crank and its backwards Octa-joint bottom bracket. In order to remove the cups, you need an early Shimano freewheel tool, TL-FW20. These are rare but can be found. It fits the splines in the cups and they unscrew like other English-threaded cups: right side cup is left-hand threaded.
Might possibly also be an old non-FFS Selecta crankset using the same Octa-joint spindle/cup/crank/chainring design.
Strange old Shimano crankset? pics
https://velobase.com/ViewGroup.aspx?...3-dbe7b7f236eb
https://velobase.com/ViewComponent.a...e8875&Enum=115
https://www.google.com/url?sa=t&rct=...w&opi=89978449
Sorry for the ridiculous length of that last URL, but Google for some reason grossly obfuscates links in their current search results and I don't have the patience at present to interpret it down to more reasonable form. Also, while the Velobase entry for the crankset (third URL above) indicates a 22x1mm extractor is used, I think that's only for removing the crankarms. I believe this setup uses the same tool Jeff Willis indicates above for removing the FFS BB cups.
OP: Best of luck. If you're planning on restoring the bike to original and don't have the rest of the crankset parts, be advised that you might have difficulty finding the rest of the crankset. They're somewhat rare and
very non-standard for the era. If you're not planning on a full restoration to original, destructive cup removal (as dddd suggests) is thus an option.