TOKYO - It all began with a penicillin jab in his backside as a teenager.

Masafumi Nogimori saw first-hand how drugs were effective against infection, and so began a life-long love affair with the pharmaceuticals industry that has taken the 62-year-old CEO of Japan's Astellas Pharma Inc to the brink of the firm's biggest takeover deal.

Astellas, the country's second-biggest drugs firm on Monday went hostile with a $3.5 billion offer for U.S.-based OSI Pharmaceuticals, best known for its Tarceva cancer drug.

While his peers at rival Japanese drugmakers Takeda Pharmaceutical, Eisai and Daiichi Sankyo have already cut billion-dollar overseas deals that have raised their profiles, Nogimori is seen as a humble, ordinary man, with plenty still to prove.

Hostile overseas takeovers are not the norm in Japan, and this is Nogimori's second in little more than a year -- after Astellas refused to raise its $1 billion bid for CV Therapeutics and lost out to Gilead Sciences.

Analysts who cover Japan's drugs sector say Nogimori is modest and cautious -- in contrast to the more charismatic, risk-taking leaders at Astellas' rivals.

He doesn't show emotion and gives me the impression of being a logical person. Nogimori-san seems to be an ordinary man, said Credit Suisse analyst Fumiyoshi Sakai.

Some industry insiders and analysts have dubbed Eisai's CEO Haruo Naito Emperor, while Takeda boss Yasuchika Hasegawa is said to be feared by subordinates, including local researchers struggling with his order to use English in meetings. Daiichi's president Takashi Shoda has a reputation as a decisive leader.

Nogimori, who speaks slowly and often with a bashful smile, can, however, surprise and disarm with totally unexpected jokes, one Astellas staffer said.

At an internal banquet where we were all expecting him to say what a CEO would normally say, Nogimori-san surprised us by saying: 'I'm here to drink with you all', said the employee, who asked not to be named.

SEEKING MIRACLE CURE

The youngest of four children born to a family that ran kimono and textile dyeing businesses in Japan's central Aichi prefecture, Nogimori once said in an interview that his passion to become a pharmacist began at junior high school with those penicillin shots.

He went on to study medicine at Tokyo University and joined Fujisawa Pharmaceutical which merged with Yamanouchi in 2005 to form Astellas -- meaning Aspired or Advanced Stars.

Decades on, Nogimori's passion for the pharmaceuticals industry remains undimmed, as does his love for collecting fossils and relaxing with Japanese calligraphy.

When Astellas opened a costly R&D center in 2009, Nogimori was asked what he hoped it would produce.

Our aim is to find medicines that can satisfy unmet medical needs. I hope for such an unknown miracle, he replied.

But Nogimori is also a pragmatist and knows the odds of discovering new blockbuster drugs are stacked against manufacturers.

In an interview with President magazine in 2008, he acknowledged the chances of producing a new medical product were just 1 in 19,700.

But simply waiting for such a miracle doesn't produce anything. Endless effort, even if you know that would end up as nothing, will help you see that miracle. In other words, nothing is meaningless, he said.

(Editing by Ian Geoghegan)

Japan