Jun is childhood friends with two twin girls with different personalities. He ends up in a love triangle with Rumi, who looks boyish but is an otome (maiden) on the inside, and her twin sister Naori, who is a cute otaku.

Jun Shirasaki and the Jinguuji sisters are childhood friends and neighbors. When Jun's first girlfriend, the older sister Ryuumi, breaks up with him, she says something that complicates the three people's relationship, their first loves, and their romance-?—MAL News

Koi wa Futago de Warikirenai, written by Shinon Takamura, follows a boy named Jun as he falls in love with the twin girls who are his childhood friends and live next door; both of which who couldn't be more different from each other. Rumi, the older sister, who has a boyish exterior but a maiden-like personality while Naori is super girly and also a super otaku.—Crunchyroll News