Atop the Sogyoku Hill...
“Aizen, the power of a Soul Reaper has its limits. In a short time, I've come to understand one thing.”
“The more you scheme, the more you realize that a Soul Reaper's abilities have limits...”
“Unless you go beyond being a Soul Reaper...”
Aizen: “Kuchiki Rukia! What exactly are you trying to say?”
“I'm done being a Soul Reaper, Aizen!” She pulls out the Hogyoku.
A story about an unlucky person who transmigrates into Bleach as Rukia, then travels through various worlds to grow stronger because she doesn't want to go through the same things as in the original story.
Main world: Bleach
Worlds visited so far: a high-martial-arts version of Demon Slayer, the Type-Moon Fourth Holy Grail War, Naruto, a parallel world of Bleach, and The Garden of Sinners
Current progress: Bleach main world
(This story contains additional worldbuilding, so please don't get too hung up on the original. Of course, if you spot any major plot holes, please point them out in the comments and I'll do my best to fix them. If I really can't, just consider them part of the alternate setting... The first volume is rough, so I recommend skipping it.)