I suggested languages which I can use, and the interviewer said Java is required. If you are familiar with the Java language, the interview will be easy. If you are not, it will be difficult.
What is your main language?
The following metrics were computed from 2 interview experiences for the Rakuten Web Engineer role in Japan.
Rakuten's interview process for their Web Engineer roles in Japan is fairly selective, failing a large portion of engineers who go through it.
Candidates reported having very negative feelings for Rakuten's Web Engineer interview process in Japan.