Undated photo of Tokyo Fire Captain Yukio Takayama and 19-year-old daughter Chiemi Takayama. Photo courtesy of Takayama's talent agency, CTU Inc. (Courtesy of CTU Inc./COURTESY OF CTU INC.)

What might terrify a man more: Rushing into an overheating nuclear facility in the dead of night? Or opening the pages of the national tabloids to find sexy photos of his 19-year-old daughter in her underwear?

For Tokyo fire captain Yukio Takayama, that scenario was more than an abstract riddle this month. As the leader of the elite rapid-response unit that drenched the crippled Fukushima Daiichi plant with thousands of tons of seawater on March 18 and 19, Takayama, 54, toiled for 30 minutes just a few yards from the radiation-spewing No. 3 reactor.

Along with his colleagues, Takayama was hailed as a hero at a nationally televised news conference next day. It was a proud moment. Until his daughter Chiemi — a “gravure idol,” as the Japanese call young women who pose for sexy photos in skimpy outfits — revealed on her blog two days later that Takayama was her father.

The disclosure thrilled the tabloids, which published stories featuring Chiemi’s bust size and photos such as the one of her in rabbit ears and leopard-print lingerie that appeared in the Nikkan Gendai newspaper on March 26. Besieged by interview requests, Chiemi, who studies economics at Tokyo’s Komazawa University, held her own news conference.

“It is embarrassing to say at my age, but I really love my father,” gushed the modestly dressed Chiemi, according to a YouTube video that has been viewed more than 95,000 times. “I wanted everyone to know his greatness, that he is engaged in this work to save people’s lives, risking his life.”

The unpredictable turn of events has proved one thing about Yukio Takayama: He has an inner fortitude to match his lean, hard-boiled firefighter’s exterior. The father of three didn’t blink in the face of either challenge.

“My daughter wants to be a gravure idol. I can’t stop what my daughter wants to do,” Takayama said in an interview at the firehouse in Tachikawa City, west of Tokyo. “It’s not like she’s getting naked.”

Takayama had other things on his mind when he got the call from his boss at 9 p.m. March 18 telling him that Prime Minister Naoto Kan had ordered Tokyo’s rapid response team to Fukushima to set up a pumping operation. The Fukushima Daiichi facility was badly damaged by the March 11 earthquake and tsunami, and the No. 3 reactor was headed toward a meltdown.

Within minutes, a caravan of fire trucks and water-cannon pump trucks was racing north toward a danger that, unlike the smoke and flames the men were used to, cannot be seen or smelled.

“No, no, no, we didn’t even have basic knowledge about radiation,” Takayama said emphatically, when asked if the team had been trained for such a scenario.

At a staging area about 20 miles from the plant, Takayama and his men were given only vague instructions from Tokyo Electric Power Co., which operates the facility. They had no map as they drove into the darkness and pulled the lead fire truck between reactors No. 2 and 3. Workers holding monitors shouted out the changing radiation levels in the air as the men, wearing protective clothing, hooked up a 220-pound fire hose to the super-pump truck drawing seawater from the ocean.

Finally, the water came, shooting through holes in the walls of the damaged reactor. The men set the pumps to automatic and raced to safety in two minivans.

Chiemi Takayama, meanwhile, was away on a work assignment and had no idea her father had been in the danger zone until a friend e-mailed her. She later explained on her blog that her mother had not told her because she did not want Chiemi to worry.

On March 22, writing on the blog, she revealed her family connection. The following day, she posted another entry defending her work as a gravure idol, saying she does it “to make people smile.”

In Japan, gravure idols occupy a murky middle ground between show business celebrities and porn stars. Many see it as an entry point to a career in television and movies.

“This has been my dream since I was little, and my father is supporting me,” Chiemi wrote.

On March 24, Chiemi held her news conference, generating tabloid headlines and a more sober wire service story. Anonymous commenters on YouTube and celebrity gossip sites complained that she was elbowing in on her father’s sudden fame to promote her recently released second DVD, titled “Miseinen,” or “Underage.”

Takayama said Chiemi asked whether he was embarrassed.

“I said, ‘You haven’t done anything wrong,’ ” the fireman said. “I was surprised by how the mass media dealt with this.”

Chiemi, her father said, gave him a handwritten note.

“I wrote what I’m always too shy to say: ‘I am proud of you,’ ” Chiemi said at the news conference. “My father hardly talks at home, but he thanked me for the letter and said it made him happy.”

Special correspondents Kyoko Tanaka and Akiko Yamamoto contributed to this report.