Ryo Shibuya, one of the plaintiffs in a lawsuit against the town of Yamamoto, Miyagi Prefecture, lost his 2-year-old son Ayumu in the 2011 tsunami.

The boy was one of three children from a public nursery school who died when the car they were fleeing in was engulfed by the huge waves.

Shibuya, 30, said his son's voice, encouraging him to say "good luck at work" — the words he had just learned — stays with him. But he is trying to move on with his life as he believes "Ayumu is happy to see his dad strong and always smiling."