Yui discovers her best friend's naughty secret and gets caught up in a wild, kinky threesome with the class nerd

Yui Nanami doesn't understand why her best friend Tsumugi Shijo doesn't want to walk home together anymore, so she follows her after school and sees her making out with the creepy class nerd, Kuzushima! Before Yui can tell anyone about the puzzling sight, everything goes black and she wakes up in the equipment shed. She watches in disbelief as the pretty, popular girl sucks the nerd's cock and eagerly swallows his cum, and soon she's doing more than watch as Kuzushima puts her on a leash and teaches her to give in to all her dirtiest impulses, from sucking cock to shamelessly pleasuring herself as Kuzushima fucks her best friend... and then it's her turn!