Hope it's cross buy! But seeing as it's a Japanese dev, it probably won't be.
Yeah, it's usually just American companies that do cross-buy, since they believe in freedom.
....or rather, it's usually indie devs who need to make their pixelated Terraria clone seem like as good a value as possible while still making money within the slim margins usually seen in the gaming industry.
On a side note: is it really bad that when I looked at the American flag gif, it took me three tries
to recall the correct anthem, despite living in the US my entire life? XP