When Splinter and the Turtles went on vacation and asked April to watch the lair, she was expecting a very boring few days until they came back. That's why she was pumped when the perimeter alarm actually went off and she saw a strange looking Yokai trying to force it's way in. Bat in hand, she burst out and excitedly flung herself into battle, but her eagerness soon turned to confusion as the battle progressed. Every blow from her bat or flying kick that she landed, the Yokai would be engulfed by a strange glow and it's height would slightly reduce. This was actually a very powerful magical ability, no matter how powerful the blow the Yokai's body wouldn't take any damage and would only lose a tiny bit of size, which would slowly revert in time anyway. In a closely matched fight it would give them a massive advantage against their opponent, but it was quickly learning in this battle what the flipside of that benefit...
Despite being a mere human, April's fighting prowess was miles ahead of the arrogant Yokai, and she rained down blows onto them without giving it a second to breathe. The Yokai's height shrank further than it ever had before, which also killed what little chance it had of turning the tides. Their pride still made them hesitate to beg however, and their stubborn silence only infuriated April more. She'd gotten her hopes up for an actually epic showdown, and ruthlessly vented her frustration on her enemy turned punching bag until it barely reached her waist. The Yokai futilely started launching punches of it's own as April stopped to take a breath, it's puny blows only serving to tickle and enrage it's opponent further. Keeping her bat at her side April sent the Yokai tumbling backwards with a single knee, before launching a series of stomps and kicks onto it's prone form. Their size rapidly dropping even more the Yokai finally swallowed it's pride and started begging for mercy, but it's pathetic squeaks were ignored by it's unhappy tormentor. The Yokai was soon no bigger than a rat, and April stopped her endless stomping to simply grind it underfoot. The Yokai was twisted and scraped against the filthy sole of her sneaker, ground out like a cigarette butt beneath the giantess until they were shrunken to the size of an insect. April's massive shoe finally lifted off of them as the massive human took a step back, the Yokai gazed vacantly upwards as it thanked the cruel goddess for finally taking pity on them. It's mind could barely register the horror it should have felt when April's now bare foot was raised above them, the Yokai not even thinking to scream before her mercilessly sole slammed down and everything went black.
That was the end of the Yokai as far as April was concerned, a pathetic death fitting for someone that had completely wasted her time. But the grim reality for the Yokai in question was that they had avoided a merciful beneath her foot, remaining battered but alive and completely embedded in the pungent flesh of April's unware sole. They were sandwiched between her reeking foot and the swampy insole of the boot she had slipped back into, and every step the giantess took shrunk her unwilling captive further. The Yokai would eventually shrink to the level that her foot couldn't crush them any longer, but they were only able to regrow to the point that it could yet again. They would spend an eternity beneath April's unknowing tread, sentenced to a far worse fate than the ruthless goddess had even planned for them...