Story Behind Jeju Island of Solo Leveling You Don't Know.

6). Jeju Island incident took place 4 years before the start of the series. Also, it's a highly significant event in Solo Leveling.

5). A bad thing happened on Jeju Island 4 years ago before Solo Leveling. Strong monsters escaped and defeated hunters. These creatures caused violence and they are also called Dungeon Breaks

4). Korean government sent hunters to Jeju Island multiple times, but they couldn't defeat the monsters. The creatures are born with incredible powers.

3). During the Jeju Island raid, S-Rank Hunter Eunseok died. The anime's opening scene shows White Tiger Guild and S-Rank Hunters saving friends from giant ants.

2). Eunseok famous hunters, died in a failed battle on Jeju Island. After his and multiple hunters death, the Korean government decided to give up on trying to recover the island.

1). Baek Yoonho feels guilty for not finding Eunseok's body after the Jeju Island event. Choi Jong In tries to use this guilt to recruit Baek for another attack on Jeju Island.