New hire is destroying our work-life balance and I'm losing my mind

Okay so I (29F, 5-year assistant manager) need to vent because I am SPIRALING.

Two months ago we got a new hire. Same age as me, same title as me, except she's technically a "6th year" because she's switching industries. First impression? Super agreeable, seemed great. But the longer we work together the more I want to scream into a pillow.

Because she is making the rest of us look bad. Like genuinely unhinged levels of trying hard.

**1. She works through lunch. Every day.**

Our department gets a TON of calls. Three years ago I had to fight tooth and nail for guaranteed lunch breaks. A senior manager who eventually quit literally went to bat for us and WON. That was hard. That mattered. When we handed off responsibilities to the new hire we specifically told her: do not take calls during lunch. She takes the calls. She eats while working. Today? She didn't eat at all. She just. worked.

**2. Unpaid overtime. Voluntarily.**

We have an overtime pay system where you apply in advance and get compensated. The company actually discourages overtime, so most of us only stay late when it's urgent. This woman started doing unpaid overtime on her THIRD DAY. Doesn't even file for the pay. And because of her I ended up staying late without filing twice (she grabbed me on my way out with questions :(( ). Now management is starting to compare. "She does it, why don't you?"

**3. Won't take breaks.**

Our office is actually really nice?? We have gaming setups, massage chairs, a nap room. Sometimes our team lead takes us all there for a quick 30-minute chill session. She's never come. Not once in four times. "I have things to finish" she says. So now our team lead has basically stopped organizing group breaks because "she seems busy" and we should all just figure it out ourselves. The break culture we had is just. gone.

**4. Won't use the company card for coffee.**

We all get individual corporate cards. About 300,000 won a month (~$230) for lunch and coffee expenses. She uses her own money. Every time. Says she wants to "save the company money." GIRL. WHAT.

**5. Buys her own office supplies too.**

Same thing. Won't submit supply requests, just pays out of pocket. For pens and stuff. With her own money.

Okay look. I know it's her choice. I get that. But here's what's making me actually lose sleep: the rights we have at this job weren't given to us. Someone fought for them. Someone argued and pushed and probably got yelled at so we could have lunch in peace.

And she is quietly erasing all of it.

We're always going to be workers. Management will always want more. The only way to protect what you have is to hold the line together, and she is just casually blowing past every line we drew.

Already got the "she does it, why can't you" comment from a manager. Four of us share the same duties. I know what's coming.

I genuinely don't know what to do. She's not a bad person. She probably thinks she's just working hard. But I am so stressed.