An unappreciated green cicada sits behind a computer every day, doing data entry for a nameless organisation.

In 17 years, he's never made a mistake or taken a sick day.

This strange, suit-wearing insect is the hero of Cicada, the latest book by award-winning author and illustrator Shaun Tan.

Tan says he was interested in the concept of a bug working in a human environment, where nobody is surprised by his presence.

"Nobody around him ... they don't question it at all," he says.

"They see it as an opportunity for getting some really good, error-free, boring work done without any additional cost to their corporation."

Award-winning author and illustrator Shaun Tan says the meaning of his latest book is unclear even to him. ( Supplied )

In fact, the insect is treated terribly by his human workmates.

He is in turns bullied and ignored — banned from using the office bathroom, and never given a promotion.

On the day of his retirement, with no party and no handshake, the cicada decides it's time to say goodbye.

He heads to the roof of his grey office building, where an unexpected transformation takes place.

Insects, robots and monsters

While a wide-eyed bug in a suit might seem like a strange idea for picture book, it's a comfortable fit for Tan, who has spent a career creating dream-like worlds of monsters, machinery and oversized animals.

His acclaimed 2006 book The Arrival tells the story of a migrant arriving in a confusing new world of floating objects and unusual creatures.

In The Lost Thing, a boy discovers and befriends a bizarre-looking metallic creature while collecting bottle tops at the beach.

That book went on to be turned in to a short animated film — which won Tan an Academy Award in 2011.

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For Cicada, Tan researched the life cycle of cicadas, which can spend more than a decade underground before shedding their exoskeletons and revealing new wings.

"Some species have this 17-year life cycle, which seems crazy long and unnecessary for an insect of that size," he says.

Search for ambiguity

There are clear parallels between the life cycle of the cicada and Tan's story of corporate drudgery.

But the author says the meaning of his book is unclear, even to him.

It's an ambiguity he actively strives for.

"A number of times I've written a story or I've painted an image and I find it frustrating because I understand it too clearly," he says.

He rallies against illustrations that appear too real, or when the expression on a character's face is too descriptive.

"I want it to actually present a mystery that's very clear on one hand, but really open to interpretation, to the extent that I don't even know what it's about," he says.

"If I can get it to the point where it's just hovering on the edge of understanding, then I know that I've got something."

Shades of grey

While Cicada is a picture book, it's not necessarily written for an audience of children.

Cicada's protagonist has to navigate a drab corporate environment with hostile colleagues. ( Supplied )

Indeed, it bucks many of the usual story book expectations.

It talks about things that adults understand — data entry, and human resources departments — and it's almost completely devoid of colour.

The story is told in monochromatic shades of green and grey for the majority of its 32 pages — familiar territory for Tan, whose book The Arrival was illustrated solely in sepia tones.

The artist says before starting a book, his first question is whether it needs pictures at all.

"When I do have pictures, it's like, to what extent does it need pictures and element of pictures?" he says.

"Often it needs very little, including colour."

And as for who his audience is, Tan can't really say.

"I don't really know, myself," he admits.

"All I can think about, rather selfishly, is my own preoccupations and idiosyncrasies, and just try to make the book look good for myself.

"It's quite hard to think about other readers. I trust that they're not too different to me."