Thank you all for leaving comments and contributing to this quiz.
As before, let's see what this aircraft is not.
Not a Tachikawa Ki-74. Good suggestion, though.
Not a Mitsubishi G3M "Nell". The dorsal blister had thinner frames and couldn't be opened forward.
Could it be a Mitsubishi G4M "Betty"?
The radio antenna mast is in the wrong position. Instead of being on the port side of the dorsal blister, it's in front of it.
There was one more "Betty" type with this kind of antenna position. The G6M1-L2 transport.
You can see the differences in this FAOW illustration.
And here's a very good photo showing the blister opening forward.
It's my impression that the dorsal blister of all early "Bettys" could open forward.
I think it's an interesting small detail that could make a diorama of a "Betty" getting maintained on the ground even more special.
Brett and Kevin Bade correctly identified the type and sent over some photos. Thanks Kevin!
Of course, for those more versed in the development history of the "Betty", it's a moot point whether the original photo shows a G6M1 escort fighter or a G6M1-L2 transport.
Thanks again everybody for leaving a comment. I hope you enjoyed this quiz. More coming up!