TOKYO, June 12 -- For centuries, exhausted parents have relied on a familiar checklist when a baby starts wailing: hungry, sleepy, wet nappy, wind or simply in need of comfort.

Now, a growing number of parents in Japan are adding something else to the routine - artificial intelligence.

Meet the latest entrant into the booming world of parenting tech: apps that claim they can translate infant cries into actionable advice, turning late-night guesswork into something that looks a little more like a diagnostic dashboard.

One of the buzziest newcomers is Babylingual, a free app launched in March by 25-year-old Japanese father Moto Numazawa. The idea came not from a Silicon Valley lab, but from the living room of a first-time parent trying t...