A total of 92 people died in the fishing town when the tsunami struck.
Mr Key makes a short speech which touches the right bases. His visit is purely symbolic. He has stopped off in Japan on his way back from Apec for two days to mark the sixth anniversary of New Zealand-Japanese diplomatic relations.
Predictably, he agrees the tsunami and the Christchurch earthquake have strengthened relations.
Barring the long-running argument over whaling, the relationship has always been strong even if New Zealand would like to see a cut in Japan's punitive food tariffs.
Mr Key's visit is much appreciated by the locals, however. As a Ministry of Information spokesman points out, the biggest worry of residents is that the world has moved on too easily from the cataclysm of March 11. The visit is topped off by a memorial service for the dead. The speeches are worthy, but predictable.
Then the Japanese-based kapa haka group Nga hau e ha take to the stage. The haka is complemented with a rendition of Pokarekare Ana. It is a long way away from the feudal aristocracy of the samurai. Suddenly we seem a lot closer.