Soto (外): outside. The Daijisen dictionary also defines it as people or places other than those concerned, an outsider, another person. One of its examples is kimitsu ga soto ni moreru, a secret leaks outside.
Miuchi (身内): followers of the same boss. Also, members of the same organization. A dictionary example: miuchi no fushōji o inpei suru, to cover up a scandal among one’s own.
Haenuki (生え抜き): born and bred. An HR glossary explains a haenuki employee as one hired as a new graduate, not a mid-career hire or an employee on loan from elsewhere.