My answer to both questions would have to be the PS4. Everything that the PS1 was, the PS4 has improved on and will continue to pass. The amount of games and the content of the games that will be on there by the end of the consoles life will most likely be untouched by any system ever.
Btw, Im jealous of you living in Japan and would love to go there.
I am not one of those overly nostalgic guys who thinks that everything was better in the past, but, although owning the system since it's launch, I don't think the PS4 has (nor has it the potential to have) a very good library... In fact, I would say that unfortunately it is on the way to be the worst Sony console ever in my understanding... So, I would love to hear from you what makes you like it so much.
Oh! And if you happen to be in Japan someday or need something from here, just let me know! It is far from the best place in the world to collect for the Master System and Mega Drive, but it is great for almost everything else!
Also, hey! Hook me up with some cheap Godzilla figures from over there! lol
Haha! Godzilla figures and memorabilia can be found in abundance and almost for free around here. If you are looking for any particular stuff, I can check it for you.