well it is Hayate Gekko

released at 24th December 2019 on CN server as Secret Ninja

hint 1: male

hint 2 Konoha

hint 3: strong cough

hint 4: guide chunin exam

why it cant be Genma ? because he was released at 30th june 2020 on CN servers in 3vs3 and is no secret ninja and because of the last two hints.

why cant it be Chiriku ? because he is now in the Secret Ninja paket

why cant it be Yota ? same reason like Chiriku

why cant it be Hiashi or Kotetsu ? both where secret Ninjas this year and cant be it two times in different seasons.