what is the star plasma vessel

In the anime and manga series Jujutsu Kaisen, the Star Plasma Vessel is a young female who is compatible with Master Tengen, an immortal jujutsu sorcerer who needs to merge with another human, the Star Plasma Vessel, to stop the evolution process and put an end to their aging process. This merging needs to happen once every 500 years to reinvigorate Tengen’s immortality by rewriting their body’s genetic information. The Star Plasma Vessels are always young women who can put an end to Master Tengen’s aging, and once the merging is complete, the vessels can communicate with each other, even though Master Tengen cannot communicate with them. The vessels are born every time in the time of need. The Star Plasma Vessel is a human vessel needed by Master Tengen to keep from evolving past their humanity, which would push them past empathy and understanding and spell demise for the world.