My One-Hit Kill Sister - S01

Asahi Ikusaba, an ordinary otaku, gets pulled into another world while rescuing a child. At first, he thinks he’s been reincarnated with overpowered "cheat skills" like the protagonists in his favorite stories-until a run-in with a deadly monster shatters that illusion, proving he’s still just a regular person. In desperation, Asahi cries out for his doting sister, Maya, who suddenly appears-except "she’s" the one with the godlike abilities he assumed he’d have. Thrilled to reunite with her brother, Maya vows to shield him at all costs. Now stuck in this strange world, the siblings try to enjoy their adventure while searching for a way home. But as the Demon King’s unstoppable army marches closer, it becomes clear their arrival wasn’t an accident. With no one else strong enough to oppose the threat, Maya may be the only hope.