Can I get a faculty job in the UK without UK experience? I have worked as an Assistant Professor in Japan for 5 years and can apply for promotion, but for personal reasons, I cannot live in Japan. I plan to apply for a Senior Lecturer/Reader position in the UK.

A friend of mine who works in the UK told me you cannot get a teaching position in the UK unless you have studied or worked in the UK higher education.

She suggested that I have a better chance to get a job in the US where universities do not expect a local experience if the application is strong at the international standard.
I am not sure what type of answer you are looking for. Based on personal experience as an American with all my education and training in the US, my first faculty position was as a lecturer in the UK. There are no laws requiring UK experience to get a faculty position of any rank in the UK. There are laws that give preference to those who have a right to work in the UK, but that is not the same as UK based teaching/education experience.

While some schools may prefer individuals with UK based experience, it was never something that came up during our searches. That said a familiarity with the UK system is helpful for demonstrating you can be a good tutor and help advise students.