Lv. 99 Princess of Black Flame

When portals called “gates” opened in 1997, humanity was thrown into chaos as monsters ravaged the planet. Countless lives were lost, including Eunha Cha’s mother. Left to fend for herself, Eunha one day mysteriously awakens a new power. Drafted into the military to fight alongside other Hunters, she sets out on what was supposed to be a routine mission inside a C-rank gate. But when she becomes trapped inside, she’s forced to fight relentlessly against waves of monsters as the gate resets endlessly... until a voice calls out to her.

(Source: WEBTOON)