A lot of very useful and versatile specials and elites lie within Japan. Most of these can go into almost any deck and not be to out of place. This is great news for when your crafting these cards becuase you won't have to worry about the card only seeing play in a single list!
33rd Recon - Being a 1 kredit card that often draws a card makes the recon a very flexible card that fits into almost any type of strategy. Any deck can appreciate 1 cost cards that draw with some minor upside. It's even possible to draw multiple cards with this through a couple different ways. Buffing it to have more health with almost always gaurentee that it will draw 2+ cards and you can evewn it make into a threat which will put the enemy in a tough spot where they don't want to let you draw several cards but also need to kill it. The other way is a bit more niche but if you have something that only deals 1 damage you could hit your own recon for more draw. This is mostly a thing to be done in decks like combo that need insane amounts of it but it is nice to remember as an option. For the most part if you are playing a deck that can use Japanese cards then Recons are almost always a good inclusion.
Sendai Regiment - This card can essentially read as 4 kredits to kill literally anything without triggering desturction effects and also able to hit the few units that would otherwise be immune to orders. However there is the downside of the enemy being able to undo that removal by killing sendai itself. Smokescreen can make that somewhat difficult without orders. So the best way to use sendai is make it as hard as possible for the enemy to remove sendai. There could be some fun in buffing its health or using counter measures that stop enemy orders but the best way is to apply massive pressure to where the enemy can't spend time killing sendai. Aggro decks are able to do this very well by using cheap units to flood the board and then usingf sendai to clear the way of anything like a guard or big unit. Those cheaper units will threaten the enemy hopefully to a point that they are unable to waste time getting their unit back or otherwise they could die. It's a very powerful card in faster lists for how effective it can be at dealing with problems.
Takasagi Regiment - Defensive garunteed value. Those 3 words sum up the best qualities of what makes Takasagi great. A 3/6 guard is pretty tough to get through and the destruction effect always means that takasagi costs the enemy at least 2 cards to deal with. Forcing them to discard can rip powerful cards out of there hand and there is little they can do to stop it outside of having a big hand. The overall usefulness this can find in any matchup makes takasagi just so useful. Although some other japanese cards in this list may be more powerful the takasagi is just so versatile that it is one of the best cards to craft should you start making specials.
Blade of the Saumrai - A single clean order that just removes whatever you target. Some big bomber or a unit someone has put twelve buffs on? Just use blade and the problem is gone. Previously Empire of the Sun was cheap enough that this wasn't worth playing but the recent changes to that card has given this a more defined role. It is a useful card to have in slower control decks where you need this powerful single target removal effect. Japan control currently doesn't have a massive prescene in the meta but this card will absolutley see play when slower decks with japan start to come around.
Empire of the Sun - The big order in Japan that makes their late game possible. If you can draw 3+ cards with this order you are getting immense value from this card becuase you got a Blade of the Samurai combined with a Mobilization (which is 5 kredits to draw 3 cards) which combined would on their own cost 11 kredits to do. Empire costs a measly 10 kredits and only 1 card so you save in two different ways. It's also extremely easy to be drawing more than this so the effet can be even more powerful. There is a downside in that this card is quite slow since you don't put anything onto the board yourself and are only drawing cards. However the sheer value this card gets is often enough to flip close games comepltely in your favor or even bring you back from the brink.