Actor Choi Woo-shik challenged himself with the Busan dialect acting in the film "Number One." He was born and raised in Seoul and lived in Canada, and this was the first time he had to use the Busan dialect extensively in a work. Choi Woo-shik expressed his burden about the Busan dialect, saying, "The dialect is not just a way of speaking but a language filled with emotion." He found it difficult to use the dialect while performing emotional scenes.

Out of a total of 37 shooting days for "Number One," 20 were filmed in Busan. Busan serves not just as a simple backdrop but as a space that supports the characters' emotions. Choi Woo-shik explained that the alleys of Busan, the old apartments, and the neighborhoods imbued with the smell of home-cooked meals deepen the relationship between Hamin and his mother, Eunsil, in the film. He said, "Busan is both a hometown and a place you want to return to in the movie," adding that Hamin's reluctance to let go of his mother gains more persuasiveness thanks to the setting.

Dialect acting was a burden for Choi Woo-shik even before filming began. He took lessons one or two months before starting the movie and refined the details on set by learning the interjections. Choi Woo-shik said, "I chose to prioritize emotional acting rather than trying to perfect the dialect." He added, "Since it was inevitable that it would be revealed that I am not from Busan, I tried not to be too fixated on the dialect during important emotional scenes."

The help from director Kim Tae-yong, who is from Busan, and Jang Hye-jin was a great support. Choi Woo-shik said, "The director and senior actress Jang Hye-jin grew up in the same neighborhood," and he realized that the details of the dialect they talked about were different. He said, "I learned that even within the same Busan dialect, the words commonly used vary by region." The word "Ap!" frequently used by Hamin in the film was also used on the director's recommendation.

The film "Number One" tells the story of Hamin, whose number in front of his eyes decreases by one each time he eats the meal his mother prepares. When he realizes that the number reaching zero means his mother will die, Hamin distances himself from home-cooked meals to protect her. Choi Woo-shik said, "It was ironic and heartbreaking that he had to distance himself to protect her," and he felt a deep emotion while portraying Hamin, who avoids expressing love.

The role of mother Eunsil was played by Jang Hye-jin. Choi Woo-shik explained, "In previous works, ensemble acting was the focus, so I couldn't deeply explore the mother-child relationship, but this time we really exchanged a lot." He added, "It was a shoot where we laughed more and cried more."

This work holds various meanings for Choi Woo-shik. He said, "Since 'The Giant' with director Kim Tae-yong, it's been about 10 years since a poster featured my face this prominently," and added, "This time, it definitely feels like 'my movie.'" Choi Woo-shik also said that this film made him think about family. He said, "Most of my friends are married and have children," and "Sometimes I think, 'I could have been like that too.'" He continued, "I felt even more how important it is to have a home and family while working on this film," and added, "I'm not against remaining single, but I definitely want to get married someday, though I don't know when."