In 1966, Yamaguchi guest-starred on episode 17 of P-Productions' AMBASSADOR MAGMA, appearing alongside his future wife Yamaguchi Chie. After this he played an active part in special effects works, but came to self-doubt in his career, motivated by an on-set incident and went back to studying acting.
During an emotional scene with an older, more experienced actor, a prop came apart. Yamaguchi's character was supposed to be upset but the incident caused him to nearly burst into laughter instead. He tried to hold back the laughter and buried his face in his hands. When the older actor saw this, he stomped on Yamaguchi's foot with full strength. The resulting pain caused tears to flow from his eyes just as the camera panned onto his character. He would later say, "that was the first time I ever felt anything real on camera. I knew that if this kind of acting could be harnessed, it was what I wanted to pursue."
Yamaguchi briefly considered going to New York to audition for enrollment in Strasberg's The Actor's Studio, but other commitments kept him in Japan. The search for truthful acting led him to join the NLT Theatrical Group. During his year at NLT he attempted to refine, and re-define, acting itself. He would carry along an actor's notebook and fully develop any character he was handed, taking as many notes as needed. He also practiced stage combat and Karate.
The well trained actor's charisma showed even in small parts such as this brief role in episode 3 of JINZOU NINGEN KIKAIDA, 1972.
His 1972 marriage to Chie would later produce two daughters. Television came calling again and, in 1973, Yamaguchi would originate the role of Yoji Yuuki, aka "Riderman" in Toei's enduring KAMEN RIDER V3. A year later he would again make television history in his first starring role, as Yutaka Daimon, protagonist of P-Productions' DENJIN ZABOGA.
Yamaguchi, Akira as Yutaka, Daimon in P-Productions' DENJIN ZABOGA
In DENJIN ZABOGA, his karate skills were put to good use as it was produced during the "Kung Fu Boom" of the 70's, and Bruce Lee styles had become a favourite of producer Kitako Koji.
Both Riderman's "Riderman Machine" and Zaboga himself were built upon a Suzuki Hustler TS250.
A busy actor, he said that he was struggling with family relations, including being separated from his mother when he was young and being left in his relatives' house after his father remarried. His wife, Chie, said of the marriage, "Even if he came home late at night, he always had a meal at home, it was a childish affair, I guess he wanted to take care of his family." Takako, his eldest daughter, also recalls he played with neighborhood children during the busy period and helped her practice riding the bicycle without helper wheels.
Yamaguchi would often add scene drawings to his notebook, having once considered pursuing art in addition to acting.
In spite of his desire to pursue serious acting, Yamaguchi's love of children motivated the actor to accept work in super-hero TV shows. He would also often participate in live shows for elementary school children. His wife Chie believes that "Because he liked children, he did a lot of this tokusatsu work, and wanted to convey the warmth of family to children because he was quickly separated from his deceased mother."
In the early 80's, Yamaguchi joined some fellow actors, as well as some of his wife's relatives, in a business venture where he became an executive at a medium sized food company. During this period, he'd still find time for family, including fishing with his daughter. Many remember "the Riderman guy" as a gentle person who cherished family.
1984 re-united him with Miyauchi Hiroshi, as Yamaguchi once again took the mantle of Riderman for the KAMEN RIDER ZX introduction, "Birth of the 10th! Kamen Riders All Together!"
On April 2, 1986, Yamaguchi felt shooting pain and went to the hospital where he was given a shot, but no permission to leave. When his wife arrived, the children told her "daddy is alright!" But after four days his condition worsened unexpectedly.
Yamaguchi died suddenly of liver cancer at the age of 41, on April 6, 1986, just 4 days after being hospitalised. The disease was chronic and had onset at around the age of 20. An incomplete will was found while organising his belongings, having been completed only as far as to what should go to his second daughter.
Yamaguchi's career was diverse and he would sometimes play heavies, such as in the Toei TV drama, SPECIAL MOBILITY INVESTIGATION CORPS, where he was a semi-regular, and in a number of period dramas.
Producer Hirayama Toru had lived close to Yamaguchi and the two had been friends. When Yamaguchi dropped by Hirayama's home during pre-production for KAMEN RIDER V3, the producer insisted "I want you to audition for KAMEN RIDER!" Hirayama said that "Yamaguchi was already a well-proven actor at the time, and a surprisingly happy person", but the role was already being given to Miyauchi Hiroshi. When the time came for Riderman to be cast, Hirayama's first choice was Yamaguchi.
Like Ban, Daisuke of JINZOU NINGEN KIKAIDA, who once cracked his skull filming a dive off a pier, Yamaguchi also suffered for his art. During a speedy scene on some dunes, his left foot was caught in a motorcycle stand, leaving permanent scars.
Yamaguchi Takako, his daughter, remembers that he was ill in his final appearance as Riderman, "Birth of the 10th! Kamen Riders All Together!", and that her father's face appeared swollen.
5 months after giving this interview, Yamaguchi-san passed away.
Immediately after his hospitalisation, the current issue of the magazine "Kamen Rider Daizenshu" containing an article and interview with him about Riderman was rushed to his home so his wife could bring it to him.
Some Tokusatsu characters played by Yamaguchi, Akira:
Miyauchi, Hiroshi (Left) and Yamaguchi, Akira (Right), in Kamen Rider V3
Butai Gekkou - Natsuki
1974 - Kamen Rider X: Five Riders vs King Dark - Yuki, Joji/Riderman