The Genius's Replacement Sister Is a God in the Interstellar World

Xi Jian, who grew up deep in the mountains, had barely left his desolate planet for the first time when a suspicious person stopped him and told him:

First, he had a long-lost fraternal twin brother.

Second, his brother was hailed as a once-in-a-century genius in solo combat and was about to compete in this year's mecha tournament with the military academy. But with just a month to go before the competition, an accident had left him in a coma.

The suspicious person, a military academy coach, begged Xi Jian to impersonate Xi Feng and compete in his place, so the team wouldn't have to forfeit due to his absence. After that, he could pretend to be ill and withdraw until Xi Feng woke up.

In return, Xi Jian would get to attend the First Military Academy for free, plus a monthly living allowance of fifty thousand starcoins.

Xi Jian, the lazy but penniless: "For my brother's dream, I won't hesitate!"

·

The First Military Academy's main team had heard all about the genius who'd enrolled that year and joined the team as a first-year student. But when they finally met him, they were sorely disappointed.

He was handsome and delicate, so frail he looked like a gust of wind could knock him over. Forget piloting a mecha, was he really just some pretty boy who'd gotten in through connections?

Qi Yan, the commander and the only one who knew the truth, had to work hard to keep the team from falling apart.

In their first match, Xi Jian was sent onto the field after a mistake. The burly solo combatant on the opposing team laughed at her openly. "So this is the legendary secret weapon? That's it?"

Comments: "Has the First Military Academy given up? If they still want to win, they'd better switch players!"

The coach was frantic and about to call her back when Xi Jian casually swung her blade. The opposing S-class mecha split open with a crack.

Everyone: "...Holy crap? What happened to the pretty boy?"

Qi Yan: "...What happened to 'she's just a country girl who's never left her desolate planet, so we need to take extra care of her'?"

Who was supposed to be taking care of whom?!

·

Halfway through the tournament, Xi Feng returned, and everyone learned that Xi Jian was an untrained orphan who had only stepped in as her brother's substitute.

The whole internet was stunned.

#Wait, you're saying the person who crushed all the other teams was just a substitute?

#The genius's older sister is even more of a genius than he is

#The First Military Academy's main team responds: LOL, we can't beat the substitute. We've already been benched

#Please tell me where I can get a sister like that. I want to lie flat while she carries me to victory!

[Bonus scene]

When Xi Feng heard that the sister he'd longed for all these years had finally been found, he woke up and rushed off in a wheelchair, tears in his eyes, to meet her.

...Only to catch his childhood best friend, the aloof genius commander in everyone else's eyes, fussing over his sister. The guy was practically sprouting a tail.

Xi Feng: ???

My best friend took advantage of my absence to steal my sister. How do I kick him away from her? :)

[The truth comes out around the middle of the tournament. The siblings team up in the second half. The heroine is the strongest. A breezy, feel-good power fantasy.]

Theme: Persevere and strive for self-improvement