Tohsaka Rin from the Animal Crossing series. Debt based characters aren't too uncommon, but its odd for Momo who never cared about money before in her life. A demon girl wants $5 for a train ticket, and suddenly Momo cares about getting it back. And then Lilith takes over Shamiko's body and demands Momo pay for various spa visits, and for some reason Momo says "Yeah fuck Shamiko, she can deal with this since its her body"
Although Momo's character has changed over time. The first time Lilith took over Shamiko's body Momo saddled Shamiko with all of the debts. But the second time it happened Momo didn't allow Lilith to use Shamiko's money, and if Lilith wanted to go to a spa or buy a milk, she forced Lilith to do a rep for every $0.10 until she paid for it by working out. Which in an ironic way is a far better deal than she'd ever give Shamiko. She forces Shamiko to pay her back every day, but with Lilith she allowed her to pay her back with just a bit of working out.
I get the idea "Hurr durr Momo putting Shamiko into debt forces Shamiko to pay her back every day, so Shamiko is forced to see her every day" but for someone who grew up poor and is afraid of debts and acrewed interest its a really shitty thing to do in a way. The entire thing was a scam in the first place even Momo admits. She purposefully fucked over Shamiko and saddled her with a bad debt she didn't even agree to in the first place, to force Shamiko into labor and stop Shamiko from ever challenging her to a fight. While at the same time telling Shamiko "If you ever want me to be your dependent you have to beat me in a fight" despite the scam being Shamiko legally can't even challenge her to a fight. And Momo has added about $150 onto the debt since then after the fancy dinner. Which is even stranger when its revealed in a later chapter that Momo put extra things on the tab even after she knew they'd have to pay for it, like drink refills. Momo is pretty twisted.