Life as a Time-Traveling Army in Honmaru [Crossover]

*I just wanted to see Bortz in a Dark Honmaru, and made up this whole story just for that. Touken Ranbu makes up a large part of the novel.*

---Blurb---

One day, the Gem Person Bortz woke up tens of thousands of years ago, before humanity had gone extinct.

To find a way home, Bortz had to venture into the human world. There, Bortz discovered that the only way to create a rift in time and space and find a chance to return was to change "history."

To change history more efficiently, Bortz got in touch with the Time Government and became a Saniwa.

Good news: The Time Government can observe the past of every historical figure, so solving things by following a formula is quick and easy.

Bad news: The Time Government preserves history. It's the Time Retrograde Army that changes it.

Bortz: ...

Oh no. I've joined the wrong side.

Luckily, there might still be a way to turn things around. They say that when Touken Danshi fully fall into darkness, they become part of the Time Retrograde Army.

Bortz took a huge step back and took over a Honmaru that had seen seven Saniwa die, and was only one step away from falling into darkness.

Let's all "fall into darkness" together from now on. No one gets to laugh at anyone else.

*

The A717 Honmaru welcomed its eighth Saniwa.

Under the wary gazes of all the Touken Danshi, the new Saniwa spoke the first words upon arriving at the Honmaru.

"I came here to change history."

The Tsukumogami: ...?

#We may have fallen into darkness, but we don't want to become the Time Retrograde Army!#

Garbage Time Government, why did you invite the enemy in???

*

A post quietly started trending on the Saniwa forum.

[Topic: Did you hear? There's a member of the Time Retrograde Army among the Saniwa, and they've changed history in two worlds!]

Saniwa flocked to the thread, leaving excited comments.

[That Saniwa took down the Three Great Families in the Jujutsu world, and turned Brain into steamed brain!]

[I also heard that Saniwa took over all of Yokohama and made themself the boss.]

[Does killing Kibutsuji Muzan ahead of time count?]

[That's disgusting. Why are there scum like that among the Saniwa?]

[Changing history like that will make all of us disappear!]

But gradually, everyone realized something was off.

[Help, the Time Retrograde Army seems to be getting smaller. Is that true?]

[Who was it that said that Saniwa was with the Time Retrograde Army? They're a savior!]

[If not for this colleague, this world would've been destroyed ten thousand times over!]

[How did they fight the will of the world all by themself?]

.

Because Bortz changed the future in which humanity was destined to perish.

Before You Read:

1. Gem People are genderless. They're stones, but the original work calls them brothers, so the pronoun "he" is used here. Since they're genderless, they may wear skirts or shorts, or whatever they like.

2. No romance. They're literally stones, so what would they do with romance? Aside from canon couples, all relationships are platonic friendships. The Touken Danshi and some other characters will develop one-sided feelings for the protagonist later on.

The cover shows the protagonist with both long and short hair.

Theme: Please, not this!