Nagi's Little Sister Is the Savior of All Worlds

[The original idea wasn't inspiring me, so I changed it. Read or collect as you like]

Nagi Mayuri has a twin brother.

That guy, Nagi Seishiro, is a genius.

Even lying around doing nothing, he can easily get great results in every field.

His younger sister is the opposite.

She's sickly and slow to react. Though their personalities are similar, being ordinary is a sin.

So, when she was five,

Mayuri, longing to transform herself, made a contract with a strange creature called the System and became a savior who would change history.

She was the medicine-taker who treated Muzan, the youngest child of the Ubuyashiki family;

She wielded the famous sword Tsurumaru Kuninaga to slay countless demons;

She prevented the Kurta Clan from being destroyed and saved people from the tragedy caused by the Chimera Ants;

She joined forces with the Six-Eyed Divine Child and a Special Grade Cursed Spirit to create a new order;

She ended the century-long feud between the Joestar family and a blond vampire.

By the time she came to her senses, she seemed to have become someone rather remarkable.

Mayuri: ...

But still.

Her original goal was to save up enough money before reaching adulthood, then spend the rest of her life taking it easy!

*

After completing her missions and retiring in triumph,

Mayuri used her hefty reward money to stay home and become a gaming streamer.

Behind the screen, she dropped her act and talked a mile a minute.

"Yeah, I stopped the birth of the progenitor of demons and even got him to mend his ways."

"The famous sword Tsurumaru? I've used it before!"

"I'll have you know I've also wiped out terrifying ants that can imitate humans and saved countless lives."

"Monsters? I did run into Cursed Spirits. One of them had a volcano for a head, and I used him to make hot pot."

"Vampires? They're super weak. I beat one into a little bun."

One day, Mayuri got a text from her brother.

[Mayuri, I met a really rich young master. He says he'll support us if we play soccer with him!]

The girl quietly put down her phone and looked with a complicated expression at the people standing outside her door:

the president of the Blue Spider Lily Group, Kuninaga, a high-ranking official in the Time Administration, the heir to the Zoldyck family, the head of the Gojo family, the adopted son of a noble Joestar family, and others.

Haha, she doesn't need money anymore.

All she needs is a way to escape them alive :)

Reader's Guide:

1. This is a long novel, a very long novel. It starts when the female lead is five. Writing long novels is my destiny.

2. I may include other series too, once I've had time to think about it.

Theme: A happy childhood can heal you for life.