Flying via Shanghai, Hong Kong & Chengdu for change of aircraft– Is transit Visa required ?

My son (Indian passport holders) will be flying from Mumbai (India) to Tokyo and during the onward journey he has to change the aircraft in Shanghai ( gap is 5 hours ) . Again while returning from Tokyo, he has to change the aircraft in Chengdu (gap is 6 hours).

Similarly (Indian (passport holder) will be flying from Bangalore to Tokyo and have to change aircraft in Hong Kong ( gap is 8 hours). Again, while returning from Tokyo, I have to change aircraft in Hon Kong ( gap is 7 hours). Do my son or myself need transit Visa?
Early response will be highly appreciated.
Thanks
Nagaraj