If you have not heard about Lee Kang-in, you can be forgiven. He is a gem to behold and as a Football Manager player you will love him to bit.
He won the Golden Ball at the 2019 U-20 World Cup and his potential ability is through the roof. Valencia have set a gigantic release clause in his contract but you can bring that down by negotiations.
Likened to Paul Pogba, Kang-in is a midfield general who opens the South Korean market for you. Thank me later for this suggestion.