Why a catfish?

For centuries, Japan explained earthquakes with a catfish.

The namazu — a giant catfish pinned beneath the islands by a god's stone — thrashes, and the ground shakes. After the great Edo earthquake of 1855, hundreds of woodblock prints turned the creature into a character: blamed, scolded, sometimes thanked. It is a folk image everyone in Japan knows and almost no earthquake app has ever touched.

We wanted SHINDO to feel calm on the thousand days nothing happens, not only alarming on the one day something does. A companion who lives in the app, reacts to the world and is pleasant to look at seemed like the right way to earn a daily open. The namazu was the obvious candidate — and, we thought, the obvious candidate deserved to be done properly.

He glows, because the deep sea does.

Nazu is bioluminescent. His chin and whiskers carry a soft light whose colour is SHINDO's quietest status display: cyan when all is calm, violet when he is listening to new data, amber under a warning, red during a real early warning, and a dim ember when he sleeps at night. You can read the state of the country from the colour of a fish, without a single badge.

He is not a video or an animated sticker. Nazu is a fully rigged 3D character — forty-eight joints, fifty animation clips, from an idle breath to a startled dart — rendered live by your iPhone behind the home-screen cards. He swims through the space, turns toward you, rests, and comes closer when he has something to say. Pinch to make him bigger; hold and drag and he follows your finger.

Weather and seasons change him, too.

In spring he plays among falling petals; in summer heat he slows down and his glow turns warm; on a rainy day he opens a small umbrella; after a cold snap he shakes snow from his fins. During a tsunami advisory or an earthquake he stops playing entirely — the companion steps back so the information can step forward.

Nazu is optional. Turn him off in Settings and SHINDO is exactly as fast and exactly as serious, only lonelier.