[Bochi Bochi no Ki (Borusiti)] Momo-chan Yamiochi Shita!? (Machikado Mazoku) [estradiol]

Momo Chiyoda has gone over to the dark side, and a panicked Yuko Yoshida finds her sworn magical girl rival transformed into something needy and shameless that won't stop begging for her hands. Protests about changing back soon dissolve into slick fingers, a gasped 'please don't stop,' and a flushed, sweating Shamiko insisting she can still keep going even as Momo trembles apart with a breathless cry. The demon girl who spent so long as the helpless one discovers she's the one pushing her fallen heroine over the edge.