Responses
In korean, minjoon said "...보고 싶어요 라고 토마가 전해 달래요"
while daiki said "나도 보고 싶다...고 토마한태 전해 줘"
and there's note in the novel translator's twitter saying that 보고 싶다 is a form of “i miss you” that literally means “i really want to see you”, it’s normally used between lovers/friends/people you consider close
hope this help (●'◡'●)ノ

i really wanna know the real dialogue of i miss you, bcs in korea if minjun said bogosipda (formal way) there is no way toma say that to his father, it should be bogosipeo informal like between father and son. and the reply too i wanna know if daiki use formal or informal cz THAT WOULD BE SO CUTE!!! if its in formal way OBVIOUSLY THEY KNOW THE MISS EACH OTHER!!!!! urghhh cuteee