[Warning: This blurb will be heavily revised, but Oda Sakunosuke will remain the protagonist.]
1.
Oda Sakunosuke died.
Oda Sakunosuke came back to life.
He got a system called the Overpowered Protagonist System. The System said the essence of being an overpowered protagonist was making everyone think you were terrifyingly powerful.
When Oda Sakunosuke transmigrated into the Jujutsu Kaisen world, he stared silently at the ugly, hideous Special Grade Cursed Spirit in front of him.
System: [Ding! The Overpowered Protagonist System is online! Host, take note: the essence of being an overpowered protagonist is being "terrifyingly powerful" and making everyone tremble at the sight of you! Main quest: become the strongest in the Jujutsu Kaisen world. The goal is to maximize your intimidation factor!]
Before Oda could say a word, the System started showering him with perks: [Newbie gift pack: infinite cursed energy! Top-tier techniques! A passive skill that gets stronger against stronger opponents! Our goal is to be undefeated under heaven!]
Oda: "..."
Gojo Satoru and Geto Suguru: "He's definitely cheating."
Cursed spirits: "Terrifyingly powerful!"
2.
Oda accidentally stumbled into a battlefield.
Seeing the short swords covered in wounds, Oda stepped in and defeated the Time Retrograde Army.
From the short swords' account, he learned that their former Saniwa was a scumbag, and some of the swords had even fallen into darkness. But their former master had powerful connections, so the others had to put up with it for their comrades' sake.
The System suddenly popped up to remind everyone it was there: [Ding! New map NPC detected! Side quest triggered: Save the Short Sword Squad! Take on the Time Government! Show everyone how terrifyingly powerful you are!]
So Oda took the scumbag Saniwa's head and won over the Time Government with love.
He became a Saniwa.
A happy ending indeed.
3.
Oda had become absurdly powerful. He'd meant to go home and visit his friend, but accidentally got the world coordinates wrong.
When Oda tore open a rift and arrived in this world, he found his friend had become the boss, and was about to jump off a building.
Oda: "?"
Oda saved his friend from another world and, while he was at it, reinforced the world. Thus Boss Dazai and [Oda] became friends again. Of course, [Sakaguchi Ango] was included too.
[Sakaguchi Ango], dumbfounded by this sudden, friendship-by-robbery: "???"
4.
As usual, Osamu Dazai went to visit Oda's grave.
Suddenly, a hand reached out of the dirt.
Oda crawled out of the ground. Looking at the clearly stunned Dazai, he greeted him without batting an eye:
"Long time no see, Dazai."
"Let's get Ango and go for a drink sometime."
Theme: Oda Sakunosuke becoming an overpowered protagonist is terrifyingly powerful indeed!
