This is a cursed win. Mate can be forced, but a draw can be achieved under the fifty-move rule.
To probe all KBBBBvKP positions, these tables and their transitive dependencies are also required:
KBBBBvKQ · KBBBBvKR · KBBBBvKB · KBBBvKP · KBBBBvKN · KBBBBvK