Honestly, the more I think about it, the more sense it makes for Falcom to get a rep via Adol. A company that has pioneered action RPGs in the beginning, Ys being a series that is still going strong and has a recent entry in IX and a Switch port of VIII, and of course, it's fairly big in Japan. To me, Hero's inclusion also entertains the idea, being that DQ had the historical impact of leading the way for JRPGs, and that series is also far bigger in Japan than it is in the West. At this point, obscurity doesn't really matter, which along with Hero's inclusion, Terry has also helped prove. Though he is a big icon in fighting games, he is no doubt smaller than Ryu, matter of fact, the amount of people that didn't even know who he was shows as much, but SNK and Terry have been impactful in their own right in fighting game history.
Adol is one of these characters, small and less recognizable, but he has had a huge impact on the genre his games categorize in.
Falcom is definitely one the companies that fits the bill very well, I certainly believe that they're a likely candidate for #5, it just makes so much sense when you think of what Falcom contributed to the action RPG genre.