@Merc huh, familiar with the company but not the game. neat.
Monster Rancher.
It was a great series, but it unfortunately wasn't that well liked over here. It was a lot like FE--it had a small but very dedicated group of fans. The fact that they didn't really try very hard to sell it didn't help--the only place I was able to obtain MRDS when it came out was by ordering it online. Wasn't even sold on store shelves. They eventually went to mobile but since then the games have kind of fallen off of the face of the Earth. 
On that note, FE3/12. No, Awakening does NOT count. Medeus promised us a return. :|
Also, Ace Attorney Dual Destinies. There's a couple (I think?) of other games that have come out/are coming out since then, but they don't actually seem to be direct sequels. There was a sequel hook at the end of AA5. (And I've grown to REALLY like Athena.)
Monster Rancher? don't think I've ever heard of it before this, but hey, that's part of why this thread is here, haha. it's a shame about niche games like that though, that's basically the story with so many games, and the devs or whatever going to mobile isn't an uncommon story either >>;
hmm, interesting take. I'd have said "FE does have sequels" but yeah, I guess if you say "a direct sequel in the same setting and soon after" or the like then FE3/12 is missing one
and the AA series is plenty active, as zac mentioned. We got AA5 relatively recently, I think it's only been a little over 2.5 years since the 3DS release of AA5, and then we got the trilogy compilation for 3DS, the iOS port of AA5, and the AA game set in the past (I think people call it "The Great Ace Attorney"), though that's only in Japanese... but even ignoring the last 3 I mentioned since they're not new AA games in English, with AA6 coming in September, that's less than 3 years between AA games. plus the AAI2 translation finished for those interested in spending the gap playing that I guess technically though there's no rule saying you can't mention a series just because it's had an entry in the past 3 years though, so it's fine. I guess I'm just saying that while I'm also an AA fan I'm not nearly as desperate for a new game there as I am with some other series, haha.
Golden Sun huh, I actually mentioned that recently despite not being a fan myself. It would indeed be nice if it got a quality sequel, it only has 3 games and the last one was released in 2010 meaning it has indeed been a long while, not to mention Nintendo lately has been even worse with their RPGs/story games in general so a quality Golden Sun entry with a good story, good character development, etc. would be really nice
@AA6's digital-only release, yeah that's a real shame but I already bought AA5 on both 3DS and iOS as well as the trilogy so idk what else I can do in order to try and convince them to give this series physical releases again, lol. it's so good and I really like my retail games but... T_T
as for the localization, I think AA5 came out in July -> October (Japan -> The West) so June -> September is a similar gap of 3-4 months or so. I guess with the game not having a lot of voice work and them not having to spend time getting a retail release done, they can push out the game a lot quicker. *sighs*
Since I'm replying, I'll add another game to the list. This one is a series I talk about quite a bit, at least recently. It's "Valkyrie Profile". A JRPG series that really only has 2 entries, a spin-off SRPG for the DS that was great, and a mobile spin-off prequel that just came out (which is solid and certainly scratching my Valkyrie Profile itch, but definitely not a true sequel as it's a dumbed-down, budget, money-making version of the game as opposed to a proper full-fledged JRPG console release).
That being said it's been years since we got Covenant of the Plume for DS, and it's been even longer since Silmeria, which came out in 2006, meaning we haven't gotten a proper new entry in almost 10 years. I think the main dude behind VP even said he has the script for Valkyrie Profile 3 (which most people think would be about Hrist, the 3rd Valkyrie—reasonably so) all done, it's just a matter of... making it, which is unfortunately a decision that Square Enix, as the publisher (and likely the company to fund such a project) would have to make, and so far it's just been "nope, no sequel for you guys". T_T
If/when I reply again I will add another game, so on and so forth. So far TWEWY and Valkyrie Profile, haha.