Since it's all in Japanese, I will go through the functions of the TennoKoe Bank here for those who are unfamiliar.
Press RUN button on the title screen.
The first option dumps the console save memory to one of 4 "boxes" on the TennoKoe Bank. Overwriting the original contents of the selected box.
The second option copies the contents of one of the 4 boxes to the console save memory. Overwriting the console save memory.
The third option allows you to swap the contents of the console save memory and one of the boxes in one step.
Whichever option you choose, you will then see this screen.
Choose which box you wish to backup/restore saved data to/from and press button I.
You will then have to confirm the action by pressing RUN with Yes selected.
Once you have completed any copying, you will see this confirmation screen.
You cannot return from this screen by pressing II, so you have to hold RUN and press SELECT to reset.
If you press RUN on the title screen and then SELECT when you see the 3 main options, you can view the contents of the console save memory and the 4 boxes of the TennoKoe Bank.
Press II to return to the main menu.
There is no way to copy individual save files around.