In Solo Leveling, mysterious gates known as “Portals” started popping up around the world years ago. These portals look like glowing cracks or fissures and have a supernatural feel. The gates are ranked from E (easiest) to S (most difficult) based on the strength of the monsters inside and the environment’s complexity.
People called Hunters emerged with special powers to battle the threats from the portals. They form guilds that manage entering portals and killing monsters. If a portal isn’t closed quickly, monsters get unleashed into the human world and wreak havoc. So, there’s great urgency around clearing each portal on time.
The portals remain quite mysterious in origin and nature. But in basic terms, they are supernatural gateways ranked by the difficulty that unleash dangerous monsters. Special monster-hunting humans known as Hunters deal with this threat. Failure to clear a portal in time has disastrous consequences.
A Red Gate means a higher difficulty level – Rank B or above. Red portals can trap people inside if they don’t clear it quickly. They must defeat the Boss or wait for it to reopen to escape. Due to the danger, only the strongest hunters should attempt red portals.
In summary, red portals in Solo Leveling indicate a high-rank threat and the risk of getting trapped inside. They are dangerous and should only be attempted by elite hunters, not average ones. Defeating the Boss or waiting for the portal to reopen are the only ways out if trapped inside.