妹の迷宮配信を手伝っていた俺が、うっかりＳランクモンスター相手に無双した結果がこちらです

Synopsis

While accompanying his younger sister Maya, a "Dungeon Streamer," as her cameraman, Rinta Suzuda is deeply engrossed in capturing the moments of his beloved sister’s adventures. However, disaster strikes when Maya gets caught in a teleportation trap and is whisked away to the boss floor! Rinta rushes after her, only to find Maya trembling before an overwhelming S-rank monster—a black dragon! In a desperate attempt to protect his sister, Rinta takes the full brunt of the dragon's devastating attack… Is this going viral? A harem? Who cares! All that matters is subscribing to his sister's channel! Here begins the tale of a unaware and unstoppable streamer who loves only his sister!