Hero

From Flyff Wiki

When you reach level 120 with 99.99% EXP as a Master, you will be able to become a Hero. Although your level is replaced with the word HERO, in the hiscores and in parties or Guilds your level will read 121. Upon becoming a hero, you will receive the Hero skill for your class. Heroes cannot level up further. Instead of the Master M next to your name, you will have a large H in a yellow box opposite where a Guild logo would be.