Ecchi o nerae!: Inuneko.

Overview:

"InuNeko" is the story of a very strange love triangle between a teacher, her student and the young man they both love. Things get really strange, though, when Yuki, the teacher played by former Miniskirt Police member Tomomi Miyauchi, switches bodies with Makino, her student played by gravure idol Charlotte Yabuki. Toraichi (Masato Uchiyama), the young man in the middle of all this isn't quite sure what to make of it all... including how Yuki has somehow inherited Makino's hairy armpits.