Isekai Trip-saki de Tasukete Kureta no wa, Hitogoroshi no Shounen deshita.

The protagonist, a temporary librarian, is a victim of various forms of harassment and lives a life full of disasters. On her way home after a long day at work, she falls down a manhole and wakes up in another world. She is captured and taken to the royal castle. Although the people there believe she is from another world, they kick her. she emerges with nothing but the clothes on her back. While wandering alone, she is attacked by thugs. She is rescued by a young man who mercilessly kills people. There is a TL and R18 version.