Christianity has not figured out how to appeal to and adapt to Japan. So the Japanese reject it.
They have good reason to based on their own experience. As such Christians need to be mindful and not push people.
If someone wants to know more about Christianity, great
Buddhism has origins outside of Japan but has been around for over 1,500 years and is deeply integrated into Japansse culture alongside Shinto.
“Buddhism is foreign to Japan so it is ok to impose [insert religion here]” is pathological.