Koreeda said in several interviews that they are alive at the end :-)
Do you remember which interview it was? I searched for some interviews to confirm if my interpretation was correct, but I didn’t find any where he clearly states that they are alive at the end. He only mentions that he wants the boys to be cheerful and excited, as if they were ‘blessing’ themselves (Korea Times https://m.koreatimes.co.kr/pages/article.asp?newsIdx=368650). While I would have liked the movie to have a happy ending, the way it is presented makes it seem weird if he were to explicitly state that they both are alive. There are so many hints that lead to the conclusion that they are dead, with the dirt on their faces being the most relevant clue, especially when recalling the conversation Minato had with his mother 🤔
I'm sure that Eun Seong would try to kidnap Hae-in and kill Hyun-woo in the next episode 🤬