Isekai Munchkin: HP1 no Mama de Saikyou Saisoku Dungeon Kouryaku

Yukito Kirihara lives to protect his younger sister Sana, so when an ogre appears looking for her, he throws himself into the fight even though it costs him his life. A mysterious woman then offers him reincarnation and provides a character sheet defining his abilities in a new world.

When Yukito spots Sana’s name on the same record, he realizes she is there too and chooses a single goal: find her at any cost. The problem is that he has only one hit point. Armed with his knowledge of role-playing game systems and a willingness to exploit every possible rule, Yukito begins clearing dungeons in the fastest and most dangerous way he can before something else reaches his sister first.