Billionaire Janitor

Fuwa Saki works in the cleaning department of the Gora Group, and nobody there knows she is the company's president. A journalist friend had told her about long-running allegations of bullying and discrimination in that department, and of employees' rights being violated, so she hid who she was and took a job on the lowest rung of the company. Her supervisors and the other cleaners humiliate her and shut her out. She means to punish the people responsible quickly, but the abuse turns out to be tied to power harassment and corruption reaching well past one department. She goes after the people involved one at a time, together with the vice president, Mizushima, who is younger than her.