"Girlfriend, Girlfriend" centers on Naoya Mukai, a high school student who confesses his feelings to his childhood friend, Saki Saki, and successfully begins dating her. However, their relationship takes an unexpected turn when Nagisa Minase, another classmate, confesses her love to Naoya. Despite his commitment to Saki, Naoya is unwilling to reject Nagisa’s feelings outright, leading him to propose an unconventional solution: dating both girls simultaneously. Saki, initially resistant, reluctantly agrees to this arrangement, setting the stage for a comedic and chaotic love triangle.

The series explores the dynamics of this polyamorous relationship as Naoya, Saki, and Nagisa navigate the challenges of balancing their emotions, societal expectations, and personal boundaries. Saki struggles with jealousy and insecurity, often clashing with Nagisa, who is earnest and kind-hearted but equally determined to win Naoya’s affection. Naoya, while well-meaning, often finds himself in over his head as he tries to maintain harmony between the two girls.

Additional characters further complicate the situation. Shino Kiryuu, a close friend of Saki, becomes entangled in the group’s antics, harboring her own unspoken feelings for Naoya. Rika Hoshizaki, a bold and confident upperclassman, also enters the fray, adding another layer of romantic tension. The interactions between these characters drive much of the humor and drama, as misunderstandings, rivalries, and heartfelt moments unfold.

The narrative balances slapstick comedy with moments of genuine emotional depth, highlighting the complexities of love and relationships. Each character’s personality and motivations are explored, providing insight into their actions and decisions. The series maintains a lighthearted tone while addressing themes of honesty, communication, and the challenges of unconventional relationships. Through its episodic structure, "Girlfriend, Girlfriend" delivers a mix of absurdity and sincerity, creating a unique take on romantic comedy.