If you're looking for manga similar to Osananajimi de Konyakusha na Futari ga Koibito wo Mezasu Hanashi (Light Novel), you might like these titles.
Shiroki Tsubasa and Amami Nanato were your run-off-the-mill pair of childhood friends. But after their parents decided to declare them fiancées, they both grew more conscious of the other, and right as a sweet and heartwarming romcom would have awaited them—Nanato was forced to move away with his mother! Five years later, however, the two of them are reunited during their first year of high school. Tsubasa aims to tell Nanato of the feelings she had kept all these years, but Nanato’s new gal friend and rival Chiba Reina won’t let her! Once the both of them realize they each hold feelings for Nanato, they decide on a bet: The one who makes Nanato confess to them wins! But what happens when both girls have practically zero experience to show and fail at every attempt of seducing Nanato?! And will the old-fashioned promise of being fiancées triumph over everything after all?!
Tsubakiya Hinata, 14 years old. As for me, Onodera Tatsuya – a teacher who just took office. Hinata is a student and an old neighbor to me. Due to her rapid development, she has become more mature than her peers, and because of that, Hinata quickly becomes the center of false rumors. But in truth, Hinata was still much more childish than she looked. In the middle stage between adults and children, a fleeting glint exists only at this moment. For those who didn’t take long to mature, the luminosity was so dim that it was barely noticeable. Then at some point it will flap its wings and fly to new horizons. So at least for now, I want to follow every step of the way while I can. Today, I will continue to face Tsubakiya Hinata.
Follows a boy named Jun who 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 maiden on the inside, and her twin sister Naori, who is a cute otaku.
First year high school boy Shin Yuki stumbles one day upon his naked childhood friend reenacting a sensual novel with an mannequin in an empty classroom. Yukino Kurose, a third year student, loved to reeanact stories with Yuki's help from books when she was a child, to discover how the characters in the story felt. This time she got herself a sensual novel and asks Yuki to help her out with her reenactment again. Otherwise she'll have to find someone else, because mannequins are not enough. After a quick deliberation Yuki decided to help her out, because he doesn't want anyone else to see her naked.