Thanks. Must add this to my list.
Like passing_thru, I’m curious also if you’ve ever tried the stuff from Japonaise. (The Porter Square location has closed – huge loss – but the Brookline location seems to be open.) They had an adzuki bean bun that sounds a lot like the one you describe, and their croissants, too, had fantastic shatter.
To passing_thru: the Japonaise adzuki bean pastry had a layer of whipped cream (not custard) that cut the sweetness of the bean paste. Don;t know if you’d ever tried it. (I used to like the curry donuts, too, though they were oily on recent tries.)
