Or if you'd prefer, Mystery Dungeon Shiren the Wanderer Sidestory - The Swordswoman Asuka Appears! So obviously, it's a spinoff from the Shiren the Wanderer series, which in my opinion are the absolute height of the roguelike genre, with very little else even coming close (in fact, the only rival the series has in my mind is One Way Heroics, and that must be a friendly rivalry, since Shiren characters have appeared in that series too).
This one just recently got fantranslated, and only partially: so far, the first "area" is translated apparently. I don't know exactly what that entails, but I've finished the first dungeon, and made a decent way into the second and everything's still in English. The story concerns Asuka, the eponymous swordswoman and a friends of the series' protagonist Shiren. She finds herself in a valley where the local ninja clan, who once protected the people from monsters, have begun robbing people and poisoning the river, and Asuka steps in to investigate. Of course, the ninjas aren't acting of their own volition, but I won't spoil anymore of the plot for you.
This mostly plays pretty much exactly like one of the regular Shiren games, with a few elements I haven't seen in the others. But even that's standard for the series, since they all seem to have a few unique elements to them. This time around, there's the Monboxes, which are items that can be used to summon monsters to act as sidekicks if you don't have any actual sidekicks. I haven't found much use for them, to be honest. There's also a new scroll/wand effect: being able to set fires that burn over a large area for quite some time, doing damage every turn to anything that's caught in them.
I wasn't keen on the graphics at first, as they eschew the series' usual high-quality pixel art in favour of pre-rendered sprites and backgrounds. The game's look quickly grew on me, though, as everything's detailed and sharp enough that it doesn't have the usual ugly blobby look associated with pre-rendered graphics. Coupled with the background music, there's a lot of atmosphere to be felt and enjoyed in this game's dungeons, too.
I don't really have a lot more to say about this game. If you like the Shiren games, this is essentially another one of them, and if you're not familiar with the series, I recommend going and playing the first game, either in its original SNES form, or its later DS port, which even got an official English release! (I'm not sure if this game even counts as being obscure, but it's been the majority of my game-playing this past week, alongside Shenmue 3. So sorry if it doesn't meet your obscurity standards!)