The Akanemaru (
History
When Janis met the God of Habaki at Mount Habaki, he was able to sense her kamuitama. He believed that she was the reincarnation of Tsugumi. He expressed guilt for not being able to stop Tsugumi from getting killed by yōkai over 500 years ago. He gave the Akanemaru to Janis with the hope that it would keep her safe. Janis carried this weapon with her throughout the rest of her journey. At the Tempest Tower, it is revealed from Sugagaki that she's the reincarnation of Tsugumi's child. Without the shard of Shikon Jewel, and the Kamuitama, as she can't go through the Bone-Eater's Well, it is unknown that she can keep the Akanemaru with her all along in the modern era as she's returning to America.