I'm in a Dark Dungeon, I'm the Last Bloodline of My Family

"Our family is in decline." When Mark woke up and saw this line of writing, he planned to hang himself on the ceiling of his college dormitory again. "The situation has really taken a turn for the worse." After arriving at the family's territory, Mark found that something was a little wrong... "If I am the last bloodline of my family, then who is the ancestor I rescued?" (Dark Dungeon pseudo-fanfic, Cthulhu, Blood Curse)