O Academy's Top Mecha Master

[Puppy-dog face, wolf-dog physique, big goofy boy × technically skilled, violent big-sis type]

A new transfer student has arrived at the Omega Academy.

He has a fair, delicate face, soft short black hair, and big, dewy eyes behind black-rimmed glasses. He looks so well-behaved that everyone just wants to call him little bro.

Unfortunately, he manages to get on the bad side of the O Academy's biggest big sister on his very first day.

Onlookers: One punch from Sister An and won't the transfer student start crying...?

*

Xu Zhian has been having a run of bad luck lately. Several of her long-term part-time gigs have fallen through, and the mecha model she's spent the better part of six months building has been smashed by the new transfer student.

Luckily, despite looking frail, the transfer student seems to have some strength. He even offers to work off the debt.

On the weekend, Xu Zhian is sprawled in front of her precious mecha, giving her little helper instructions. "Hey, you. Bring those boxes out of the storeroom for me. They're kind of heavy, so take them one at a time. Be care...ful when you carry them..."

Five boxes appear neatly in front of her. Above them is the transfer student's innocent, honest smile, while suspicious bulges of muscle show beneath his white uniform on either side.

And so things start to take a strange turn. To keep hold of her excellent (?) labor force, Xu Zhian has no choice but to engage in a fierce battle of wits with the worker himself. For example:

During physical training, Comrade Laborer stands tall among his classmates, who are sprawled all over the place. His eyes are fixed on the cafeteria, clearly planning to cross the "chicken flock" and claim a good spot as soon as class ends.

Xu Zhian sighs quietly, hooks an arm around his neck, and leans her aching body against him. She asks kindly, "Little bro, are you tired?"

"Not tired!"

"No, you're tired."

*

In an interstellar age where everyone is a soldier, humanity has evolved a second gender. Alphas are skilled fighters, Betas are intelligent, and Omegas are the only ones who are useless at both physical and mental work, so all they can do is handle logistics.

Until one day, an Omega steps onto the mecha-combat arena and knocks out one Alpha after another.

That day, every Alpha on Blue Star felt the terror of being ruled by absolute strength.

P.S. 1. This isn't a serious ABO story, and the worldbuilding is pure authorial invention.

2. Male Alpha, female Omega, older sister and younger brother romance (yes, this really is my thing).

3. The male lead is a little dumb (but sweet), so please be kind to him.

Theme: Everyone has a talent they can put to use.