Pope Francis rode in a carbon-free popemobile at his mass in Nagasaki, an appropriate choice in line with his environmental concerns.
Francis used a Toyota hydrogen-powered Mirai, customised with a stand and handrails.
He will use a similar model while in Tokyo.
The pope held a big mass at a Nagasaki city baseball stadium.
Earlier on Sunday, he demanded world leaders renounce atomic weapons and the Cold War-era doctrine of deterrence, and paid respects at a memorial for the 26 martyrs.
Environmental protection is one of Francis’ key agenda items and is also part of the theme of his Japan visit.