Kemonokko Tsuushin: The Animation - Tanukiko Pokora

Synopsis

Pokora, a chubby, thick-browed raccoon demi-human, suddenly appears at the protagonist's house. She is weak to erotic stimulation and her transformation spell quickly wears off, so the protagonist ends up accompanying her in her training, and as she transforms into a bunny suit and swimsuit, he attacks her plump body. Thanks to the training, Pokora is able to withstand it, but her biggest weakness (her anus) remains...

(Source: DLsite, translated)