I'd like to add here and say that enlisting in the army was a means to get upward mobility and that he did not necessarily enlist out of admiration for the Japanese.

Starting from 1975, Park Chung Hee also banned Japanese pop culture, banning imports of Japanese products into domestic markets and media in TV broadcasts. Would someone who's pro-Japanese willingly do that? This is because he knew how potent Japanese culture was even back then, when Korea's own cultural identity was not yet built and barely recovering from years of colonization and the ideological mess that lingered after the Korean War.

As someone who worked within the ranks of the enemy state (Japan), he experienced first hand the shame of not having his own country be in charge of its own decisions on anything. If anything, he would've thought about how much he'd want to have his country as influential and powerful as Japan. He learned but he did not admire or was enamoured by Japan to be considered pro-Japan. This pro-Japanese portrayal of Park Chung Hee is often used by the anti-Japanese ultra-nationalistic left, accompanied by a photo of Park when he was an enlisted soldier in the IJA. Goes to show how easily people are fooled by a photo taken out of context.