Abranch of christians which protested against the estabilished church.

First of all it is necessary to contextualize the established church.

At the time of Jesus  the " church" was the sanhedrin which were waiting a king and their cultural beliefs were more religious that other thing.

If this the context the people that didn't follow their ( Sanhedrin) rules were considered as protestants.

But after Jesus time the any denomination which protest against the established. Originally the established church was the catholic church.

The protestant movement ( Reform around 1500) is a big branch of christians which protested against the established chuch.

i'd assume india mainly because of how isolated japan was.   plus it is a whole china away.