That plane has had its dorsal turret removed. Why?
This plane was a conventional bomber to begin with. As things were going badly with the Japanese towards wars end they started to modify aircraft into Kamikaze flying bombs. This aircraft was in process of that change but was not completed. Dorsal turret was taken out & plywood sealed off the hole. Waist gunners positions were eliminated. Nose gun removed & a pole was placed in front of the aircraft that acted as a trigger when it impacted its target the rest of the aircraft was packed full of explosives.
Few more pictures of sister aircraft in process as well.
This is what it would have looked like when finished.