The keyword is hexadecimal, and removing an useless H.E.H.U.H.E. from the flag. The flag is in the format CTFlearn{*}
File: THE_FILE
Solution:
open the file using bless or any hex editor
Search for the string CTF
CTFlearnHﾺ{fl4ggyfHﾉEHﾉUHￇE￠l4g}
Remove the H.E.H.U.H.E
CTFlearn{fl4ggyfl4g}
Flag: CTFlearn{fl4ggyfl4g}