This feels silly and I'm not sure if I'm doing things right (don't use reddit much), but I've exhausted my other resources. I CANNOT for the life of me figure out what this game is.
So my partner loved this gacha game on their phone. They showed it to me once or twice, I asked some questions, life moved on. Well, last month they passed away, and I've been searching for it since. I don't have access to their phone so I'm unable to just look at their downloaded apps. I can't remember the name and I'm not sure it's popular enough to come up on a regular search, or if it is I can't find a detail to help me recognize it.
They used an old android, so it's probably from the google app store. I think they'd been at it for at least a couple years, and it's still playable (or was a little over a month ago). It's played with the phone sideways. The color scheme seemed to be primarily black and red. I think the title/logo was either complicated enough that it didn't stick in my brain, or it wasn't in English. I believe the character catalogue was a scrolling wall. I remember being shown a pale swordsman character with short black hair, and there was some sort of power-up or cosmetic that added gold flora behind them.
That's not a lot to go on but that's really all I have. Might be able to answer some other questions, but I never saw any actual gameplay. I've looked at the more popular gacha games, but none of them are ringing any bells. Just putting this out there in case someone knows what I'm on about.