The assassination of Riko Amanai is singlehandedly the most important event in the thrilling plot of Jujutsu Kaisen. Being the Star Plasma Vessel, her sole purpose was to merge with the enigmatic Lord Tengen to prevent forced evolution. The assassin Toji Fushiguro changed the fate of the Jujutsu World even after the legend of the Six Eyes user and the Star Plasma Vessel existed.

But what lead to this devastating situation in the first place? And from where did the unknown variable in the form of Toji appear? That is what we are going to discuss today and try to describe the situation in a much clearer way.

Lord Tengen and the Star Plasma Vessel

Before we discuss why, let us set up the background here for a refresher. Taking place eleven years before the present timeline, the two sorcerers Gojo Satoru and Geto Suguru were tasked with an important mission: to protect and escort Riko Amanai and bring her to Lord Tengen to proceed with his merging.

We come to know that Lord Tengen is an immortal being responsible for maintaining the balance between the human world and the jujutsu world but there is a twist.

To maintain his immortality, he is supposed to merge with a compatible body known as the Star Plasma Vessel, that being Riko Amanai at said period. More can be read about their role here.

This was a mission of grave importance. If failed to do so, Lord Tengen undergoes forced evolution which can lead them to lose their control over barrier techniques, which protect and divide the intricacies of the Jujutsu world from the human world. In the worst-case scenario, Lord Tengen can become the enemy of humanity.

Why did Toji kill Riko Amanai?

Now, some factions were brewing up plans of their own. Firstly there was Q, who was completely against humanity and the Jujutsu High and wanted to assassinate Riko to take advantage of the foul evolution but they were quickly wiped out by the bodyguard sorcerer duo.

Then came the Time Vessel Organization, who worshipped Lord Tengen but their opinion of the merger was considered a bad omen as the act of a mere human merging with a god was deemed impure. The organization came up with a plan that would go on to change the world entirely: hire the sorcerer killer Toji Fushiguro to assassinate Riko.

Hailing from the Zenin clan, Toji was born with zero cursed energy with the concept of Heavenly Restriction coming into play. This significantly increased his physical prowess. With a myriad of different cursed weapons at his disposal, he set out for his mission.

Fully aware of the people who were in between him and his goal, Toji laid out his plans. He first decided to put up a bounty on Riko Amanai’s head. His plans were not to make others do his dirty work but to keep Gojo and Geto on high alert at all times. Gojo even went as far as keeping Six Eyes active all-day long, straining himself as a result.

After returning back to Jujutsu High, Gojo was stabbed in the back by Toji, the former not being able to sense the incoming attack due to the latter being cursed energy-less. After a brief engaging fight, Toji was able to overwhelm the strongest sorcerer by using the Inverted Spear of Heaven, a cursed tool that has the ability to cancel any cursed technique, effectively killing him.

As Geto and Riko make their way to Lord Tengen for the merger, Riko confesses that she wanted to live longer but those words were deemed to be ironic as she takes a bullet to her head by Toji. Also making quick work of Geto, Toji was successful in his mission.

But it was not going to end well for him as Gojo had healed himself using Reverse Cursed Technique and was in a berserk mode. Another fight breaks up but this time Gojo was serious with his antics as he finishes Toji off with his iconic Hollow Purple.

Despite losing one of the coolest characters in the story of Jujutsu Kaisen, Toji’s act of killing the Star Plasma Vessel was a boon for the likes of Kenjaku which further helped him orchestrate Gojo’s sealing and the horrifying acts of Shibuya.

So in short, Toji killed Riko Amanai because he was hired to do the job by the Time Vessel Organization. And Riko’s death went down as one of the most impactful moments in Jujutsu Kaisen!