Good points.
The reason I even considered the position is too relocate to Japan. I’ve visited Japan every year for the last 4 years, been to every region, stayed in all kinds of accommodations and am able to recognize enough kanji that I have never had a problem for typical activities (train stations, airports, stores, etc.) Overall, I would greatly enjoy residing in Japan.
I think unless I drastically improve language ability in verbal form, chances of another position opportunity would be low, but the company that introduced my CV to Rakuten even stressed the idea that once you work there, it would be easy to move to another company. Now that I think about that comment, seems strange, but the recruiter could care less as I would just be a quick cash grab for them and want me to agree to the position.