Like many of the thousands of men who have worked at Fukushima Daiichi nuclear power plant over the past three years, Kazuto Tatsuta was driven by a sense of mission.

"I had been looking for work around the time of the disaster and wondered if there was anything I could do to help the region," Tatsuta said.

After six months working for one of the myriad subcontractors at Fukushima Daiichi, his exposure to radiation was already nearing the legal annual limit of 20 millisieverts, so he resigned.

He left with a rare insight into the realities of life at arguably the world's most hazardous industrial cleanup site. Now he has framed his memories in graphic form in 1F (Ichi-Efu), a new manga whose publication comes as Japan debates the future of its dozens of mothballed nuclear reactors.

As an insider's account, 1F: The Labour Diary of Fukushima Daiichi Nuclear Power Plant, has proved popular among readers seeking an antidote to patchy information from the government and the plant's operator, Tokyo Electric Power Company (Tepco), and at times wildly speculative media reports.

Tatsuta draws the main character in his comic. Photograph: Koji Sasahara/Kodansha/AP

Drawing on a cast of characters loosely based on his former workmates, Tatsuta leaves nothing to the imagination. There are accounts of workers' early-morning journey to the plant from their digs in nearby towns and cities, and intricate illustrations of the protective clothing they must change into, and remove, every day.

The brisk dialogue is replete with vocabulary and work practices only an insider could know. As they start their shifts, workers tell each other to "be safe"; the manga's abridged title, 1F, is the little-known nickname given Fukushima Daiichi by workers and local people.

Tatsuta says he did not consider his work dangerous and, despite the rigours of spending hours in protective clothing and a full-face mask, he never thought about quitting. His most uncomfortable moments, he said, were being unable to urinate while sheathed in his radiation suit.

Although Tatsuta was unable to take notes or sketch scenes while at work, those who have visited the plant will attest to the accuracy of every painstakingly reproduced scene, from the layout of the rest areas where he worked to the abandoned neighbourhoods that encircle the stricken plant.

"I had done some work as a manga artist before then, but I didn't apply for the Fukushima job with the intention of writing a manga," Tatsuta, 49, told the Guardian at his studio outside Tokyo.

He first considered writing a manga soon after he left the plant in late 2012. He drew and wrote the first chapter and started knocking on publishers' doors, but failed to find an editor who was interested until he approached Kodansha.

"We could see straight away that it was highly original," said Kenichiro Shinohara, editor of Morning, a weekly manga magazine in which 1F first appeared in serialised form last autumn. "It's surpassed our expectations and has obviously caught the attention of people who don't usually read manga."

The initial print run of 150,000 copies was unusually large for a work by a relatively unknown manga artist, yet sales have been brisk since it appeared in book form at the end of April. Kodansha said there were plans for editions in English, French and German.

But readers looking to Tatsuta for confirmation that the Daiichi cleanup has been left largely in the hands of unscrupulous firms with links to organised crime, and that workers are sent into dangerous areas with minimal training and substandard equipment, may be disappointed.

"As a group and as individuals, I found them all to be decent people," Tatsuta said.

"I don't have a profound message to give the reader, other than to point out that these are men who are doing their best to get the job done away from the limelight. Politicians and experts are always on TV debating Fukushima, but the workers have no voice. I hope to give them one through my manga."

Tepco posts regular updates about progress in key areas of Fukushima Daiichi and invites groups of journalists to tour the facility several times a year, yet there is much about the work of the 3,000-plus men who work in shifts at the plant that remains hidden.

"The media have left a gap in people's understanding," said Tatsuta, who prefers not to reveal his face or his real name as he hasn't ruled out a return to the plant and wants to show solidarity with his "anonymous" workmates.

"We hear a lot about what the media are privy to – the water storage problem, the removal or fuel assemblies and the like – but what I hope to do is to tell people about things that the media never see."

Drawing entirely from memory, Tatsuta takes the reader on a virtual tour of the areas where exhausted men eat and rest, the filling stations that service hundreds of trucks, buses and cars carrying workers and equipment, and the construction site for yet more tanks to relieve the buildup of contaminated water.

He suggests that there is truth, though, in reports that many of the labourers are exploited. Tatsuta answered a job advertisement promising 20,000 yen (£117) a day, yet initially earned less than half that. And he shares concerns that as more skilled workers leave because they have reached their radiation exposure limit, finding enough replacements to push forward with decommissioning will become more difficult.

Like the small number of contract workers who have spoken to the media about their experiences at Fukushima Daiichi, Tatsuta recalls his time there as a mixture of drudgery and camaraderie.

"The labourers at Fukushima get a bad press, which I think is unfair," he said. "They're depicted as rough, but they are no different from the workers you would find on an ordinary building site in Tokyo."