Masao Yoshida, the former Fukushima Dai-ichi general manager who spearheaded efforts to get the nuclear power plant under control against company orders during its 2011 meltdown, died Tuesday of esophageal cancer. Yoshida was 58.

"He died of esophageal cancer at 11:32am today at a Tokyo hospital," a spokesman for Tokyo Electric Power Co. said in a statement.

Despite concerns about radiation levels at the plant following the massive tsunami -- a report released on Tuesday found that groundwater levels of the radioactive element cesium-134 in the area had swelled by 90 times in the past three days, according to the Japan Daily Press -- TEPCO officials deny that Yoshida’s illness was related to radiation.

Yoshida was diagnosed with cancer in November 2011, just eight months after the tsunami and nuclear meltdown. I In spite of the timeline, experts say Yoshida’s illness was not characteristic of cancers caused by radiation due to the speed at which it progressed.

According to the New York Times, Yoshida was alternately praised and criticized for his role in the tsunami efforts. In the aftermath of the tsunami, critics contended that Yoshida had been shortsighted in failing to install sufficiently high seawalls. According to the Guardian, TEPCO, under Yoshida’s charge, ignored warnings from its own engineers in 2008 that their 5.7 meter-high sea walls could prove inadequate.

In a rare move, Yoshida issued a public apology after the disaster, saying on behalf of the nuclear plant, “We sincerely apologize to all local residents, the people of Fukushima prefecture, and the general public for the anxiety and inconvenience caused by the accident.” Yoshida also admitted that he had been “too lax” in overseeing preventative measures before the incident.

Yet Yoshida was also praised for his life-risking measures in the tsunami’s immediate aftermath, and lauded as something of a national hero. After the March 11, 2011, earthquake and ensuing tsunami caused the power plant to lose power and led to successive hydrogen explosions and meltdowns at three of its reactors, Yoshida took command of the disaster response and ordered workers to continue efforts to cool down reactors.

At one point, Yoshida even defied an order from the prime minister to stop pumping seawater into one of the nuclear reactors, after a backup cooling system failed.

“I can not imagine how hard it was for him,” said Tatsujiro Suzuki, vice chairman of the Japan Atomic Energy Commission. “He had to make a decision that most of the on-site workers should leave because the situation was getting worse and he also had to have some of his staff remain to work with him. That was probably the hardest decision he ever had to make.”

Yoshida leaves behind a wife, Yoko, and their three sons.