Stealing Each Other's Lovers

"I never actually came before..." Kanae is just your average college student having trouble with her boyfriend in bed. One night staying at her sister's place, her sister's boyfriend, Yukiji, mistakenly gets in bed with her instead! Kanae's got no idea what to do about the whole thing, and when she finally confronts Yukiji... he doubles down and suggests a pact to do this more?! She knows it's wrong... but can't help but think about all these new feelings...

(Source: Houbunsha)