I Entered Demon Slayer with the Traits of a Yato

System + Pseudo-Infinite Loop + Rengoku CP + Following the Plot + Happy Ending

Su Mianxue, an international student at the University of Tokyo, accidentally activates a mission-line System from the Demon Slayer world. But when she arrives in the world of Demon Slayer, the System tells her that it's actually a dispatch System from Gintama next door. To make it up to her, it gives her the traits of a “Nightsoul.” In order to get her original System back, Su Mianxue works hard to find the special NPC on her mission route.

With the System's help, she saves many members of the Demon Slayer Corps at Mount Natagumo and earns their trust by helping Yoriichi ease his curse. She also finds the special NPC, Kyojuro Rengoku, and becomes his disciple.

After learning how great the gap is between humans and demons, Su Mianxue realizes that following the plot means people will die, slowing her mission's progress. So she decides to use a clone to infiltrate Muzan's side and weaken the Upper Ranks.

To keep Muzan from reading her thoughts, she seals herself away. But the other her who grows up happens to be the one who inherited her darkest memories.

A swordsman who creates demons should commit seppuku to atone...