I have a hybrid Alphard and replaced the head unit with an Android head unit which works well except I could only get radio 2.
Looking on the internet it shows Japanese Radio is 77 to 90 Mhz and the analog TV is 90 to 108 Mhz so I had to combine both the TV and the radio antenna plugs to get the full range. This would also be the problem with a band expander unless you combine both antennas before the expander..