I'm Fine With Being The Second Girlfriend vol 1 back

A Mature-rated romance about a couple settling for second best while learning that the first choice isn’t always meant to be.Hayasaka and Kirishima appear to be an adoring couple. They walk home together, hold hands, and even secretly meet up for a more carnal kind of pleasure. But there’s one thing off about this blissful relationship: they’re both in love with other people. Hayasaka and Kirishima have agreed to satisfy their urges and find comfort in each other, and everything will end if their feelings are reciprocated by their first choices. But the more time they spend tangled up together—in and out of bed—the messier things get. Lust is easy. Feelings aren’t.