Tayutama Kiss On My Deity Ep 6 - Gender Transformations

Episode 6 Inseparable Couple
Yuuri's sister ends up with Ho stuck on her head (the phoenix is formed when Ho and Oh are combined) and Mashiro plans to bring Ho onto her side by helping him regain power and show him their kindness. This is possible only when Yuuri's sister is happy and to do this, Yuuri has to stay by her side all the time and he disguised himself as a girl to do so and constantly changes form to attend classes.