Tensei Shitara Ken Deshita

Some isekai protagonists are reincarnated as powerful warriors or skilled wizards, but our protagonist was reborn in another life as a sentient sword! He’s taken up by Fran, a desperate girl fleeing evil-doers intent on selling her into slavery. With her new weapon’s help and guidance, she’s able to strike down her captors and secure her freedom. Together, this unconventional master-student duo embark on an epic journey to liberate those in need and exact justice on the cruel of heart. (Source: Sentai Filmworks)