Since @dizzylochs already linked my post, I won’t have to do so anymore. But if you’re really going for the goal of collecting all 1st and unlimited edition Japanese sets, I can only say: good luck. Not to discourage you after you’ve decided to take on this challenge, but I have the feeling that getting a phone call hearing you’ve won the lottery while simultaneously getting struck by lightning has a higher chance to occur than completing this goal. But I guess you’ll never know until you try I guess. 
To be a bit more concrete of why I think this: I’ve collected Pikachu cards for 5.5 years now and Seviper cards for 2.5 years. I’ve only found the Japanese unlimited edition World Champions Pack Seviper card last month (which is currently incoming to my place, and will hopefully arrive soon) after searching multiple times each week for it during that time. Prior to this purchase, I had never even seen a picture of the unlimited edition Seviper from this Japanese set. I also have yet to find the Japanese unlimited edition E1 Pikachu, despite owning almost 1400 unique Pikachu cards now and needing just 22 more to own all officially released Pikachu cards in all 14 Pokémon languages. I’ve also only seen the unlimited edition E1 Pikachu four times thus far in other people’s collections (keep in mind that Pikachu is of course a pretty popular Pokémon to put up for sale or share, unlike Seviper). I also know a Voltorb/Electrode collector (@tonysandlin ) who had found the Japanese unlimited edition L2 Reverse Holo Electrode Prime card halve a year ago after searching for it for 9 years.
What I’m mainly trying to say: if trying to find a single card of these unlimited edition sets is already this hard, I can’t fathom how hard it must be to finish all unlimited edition Japanese sets in a single lifetime. 
Regardless, collecting all Japanese sets in general sounds like a great goal, and I look forward seeing updates of your collection in a future collection thread. It might also be nice to bookmark this thread, where people sometimes post live unlimited L2/L3 auctions for other collectors. Oh, and welcome to the forum of course!
I hope you’re not too discouraged from my message, since that was not my intention at all. I mainly wanted to add a realistic take from personal experience with some of these unlimited edition sets, like the E1, L2/L3, and World Champions Pack sets especially, as well as some of the BW and XY era sets which were printed years after their 1st edition counterparts, and were pretty short-printed.
I’ve seen loads of English set collectors in the past, but not too many Japanese set collectors, so I’m looking forward to your progress over time.
Greetz,
Quuador