EA Japan has been working on translating required reading from the EA Handbook, a selection of texts that provide an introduction to the project of Effective Altruism. Check the links below for currently available Japanese translations:
Chapter 1: The effectiveness mindset
What is Effective Altruism? - 効果的利他主義とは何か
Chapter 2: Differences in impact
Chapter 3: Radical empathy
Chapter 4: Our final century?
Chapter 5: What could the future hold? And why care?
Chapter 6: Smarter than us