A short news clip from the NHK collection featuring Mitsubishi G3M2-a Model 21 "Nell" bombers.
The commentator says:
"On July 7, 1941, exactly on the fourth anniversary of the China Incident, our Navy Wild Eagles flew through the clouds over Sichuan and bombed Chonqging. Thus achieved the feat of bombing the city for the 20th time. The enemy panicked during our attack and their anti-aircraft guns fired desperately but to no avail. Our Navy Wild Eagles bombed the enemy headquarters and other important targets with great success."
Although the June raids against Chonqging and their horrible results against the civilian population are fairly well documented, unfortunately we have great difficulty to pinpoint the Navy bomber units that were involved.
The still below shows the tail marking of the "Nell" but only the "406" or "408" part is visible. Before the number there is probably a katakana but it's not clear at all. Any help to identify the unit is most welcome.