Ogami-San Can't Keep It in 4 (manga)

Just when Ogami-san and Yaginuma-kun make progress in finding the right pacing for their relationship, a figure from Yaginuma-kun’s past named Kaoru Sagiyama makes her entrance. With Sagiyama’s gorgeous looks and intimate knowledge of Yaginuma-kun from growing up together, Ogami-san feels the grip of a certain green-eyed monster begin to tighten around her heart. Is this yet another test of her resolve as a dedicated girlfriend?!