I'm Fine With Being The Second Girlfriend

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.

Hayasaka and Kirishima are dating, but only because they can’t be with the people they like. Although they’re each other’s second choices, they are still attracted to one another, and what started out as a relationship of convenience soon deepens.  This delicate balance is shaken when Tachibana, Kirishima’s crush, joins the Mystery Research Club. Since the two of them are the only members, this means that Kirishima gets to spend a lot of time alone with her! Could this lead to them getting together? And if so, what will happen with Kirishima and Hayasaka?