How common is forced long-distance relocation at Japanese companies and how can I avoid it?

A lot of people I know personally have family members who got relocated by their companies to the other side of the country or another country entirely for for like ten years or longer and I've heard it typically happens once you get married and have kids, but also that it's a choice, but also that there's a lot of pressure to say yes somehow. The explanations are always vague. I have coworkers who have been relocated but they're all older dudes and it feels too personal to ask about their reasons.