Not quite 100 on how I should be tagging this.
Artist's pixiv has tagged Reimu in the post. The bloody yin-yang ord could reasonably be eithera reference to Reimu or Misumaru, since the bag is marked as level 4.

The thumbnail looked for me like Satori's severed third eye. Was glad when it was just a yin-yang orb but the blood is still concerning.