Pros
1. The English user is more friendly than Japanese user, overall average. 2. The pay is appealing. 3. They prepared a reply templates and QA now for all kinds of issues. 4. You will have a charming, friendly and nice manager(I hope she's still there). The leader is nice too. 5. Promising company(The company itself).
Kontras
1. 24-hours shift life style, Be careful of the long-term insomnia from the jet lag may caused. 2. You got a lot of thing to learn, 3. You think you can practice or improve your Japanese, not really, maybe barley. Only if you want to make your own reply template. And don't be so surprised that Japanese difficult user is that hard to deal with and annoying, unreasonable. 4. Your English ability will improved on this position, yes and no, 5. If your colleagues were at their 20s or about to be 30, and lack of the experience of living abroad, you will be likely hearing a lot of their complaints on their job or( maybe )other team members.