Kemonokko Tsuushin 4

Pokora is a plump, thick-browed raccoon demi-human who suddenly appears at the protagonist's house.
She is weak to sexual stimulation, and her transformation spell quickly wears off, so the protagonist ends up accompanying her in her training, attacking her plump body as she transforms into cosplay outfits such as a bunny suit and a swimsuit.
Thanks to the training, Pokora has become able to withstand it, but her greatest weakness remains...