By David Salazar (d.salazar@latinospost.com) | First Posted: Jul 08, 2013 10:02 PM EDT

"Pacific Rim" hits theaters this Friday and marks the first collaboration between director Guillermo del Toro and Japanese star Rinko Kikuchi. The actress and director spoke about their relationship during a press tour in San Francisco on June 30, 2013.

In the film, Kikuchi plays Mako, an aspiring pilot who has grown up under the care of resistance leader Stacker Pentecost (Idris Elba). When picking the actress to take on the role, del Toro was careful not to pick someone that would be a stereotype of the Japanese action woman. He did not want a "sex bomb" that would turn into a "man" when the battles came. Instead, he wanted someone that would bring reality and credibility to the traumatized but thriving Mako. Kikuchi gave him exactly that.

"She has a unique combination. She has fragility and strength at the same time. She's incredibly strong and brave but she is also very delicate, you know?" said del Toro. "I wanted someone that could actually give reality to this character. That she would bring real sentiment. That she would be strong but fragile."

Hunnam agreed with del Toro's assessment of Kikuchi. .

"Rinko is just the sweetest most lovely charming delicate I just thought she was absolutely fantastic," Hunnam said. The actor noted that while most cast members complained about wearing uncomfortable suits in the film, Kikuchi never said a word to express discomfort.  "Rinko never complained once. She just found this Zen place... she just would not complain."

While she may not have complained on set, the actress did tell reporters that one thing irked her during pre-production: her diet.

Mako is a skilled fighter and very fit. Despite possessing a thin frame, the actress was still forced into a workout regime to get into shape for the role. This new lifestyle took her away from the kinds of foods she loves to eat.

"Before shooting, I [was] training like boot camp: weight lifting, running on the beach, martial arts, eating healthy foods. I've never done this before. I hate it," she revealed before telling reporters the kinds of foods she normally eats. "Chocolate, Pasta, some Japanese food, French fries. You know, I love that. But I couldn't eat [any of those] at all... Also my trainer was really hard on me. I love him, but he was really hard on me."

Kikuchi recounted a story in which her trainer asked her to run to a pool on the beach. Kikuchi told the trainer that she could not see the pool but he told her that if she ran toward a certain direction, she would find it.

"I [almost] cried [getting] to the pool," she said.

Kikuchi revealed that she put on a lot of muscle thanks to the intense workout, but after shooting she immediately lost it and resumed her normal habit of eating.

When asked how she maintained her slim physique, Kikuchi replied, "I don't know. I think its [in my] genes."

Despite the intense physical training and exercise, Kikuchi admitted that working on Pacific Rim fulfilled her dream of working on an action movie. Moreover, she emphasized that the bliss of working on the film was heightened by having the chance to work with del Toro.   

"I love Guillermo and I love this movie and I knew how lucky I was to get this role," Kikuchi said. "He is such a loving person. When my performance was good he would get so happy that it made me work harder. He's special. "