Employee in training, Nakajima Hyoue, is assigned to Planning Section 7 of MATSUDA, a company known for its hiring of eccentric people. Upon arriving, Nakajima encounters a strange man hiding under his desk, protecting a stray cat. That man is none other than Kobayashi Akira, the section chief of Planning Section 7. Nakajima is drawn to his mysterious new boss, and works to get closer to him. Meanwhile, Kai Yoshimasa, acting head of the product development department, and a protective older brother figure to Kobayashi, does his best to interfere with the rapidly growing relationship between the two.

However, trouble begins to brew within the company when the data for a new project is stolen from Planning Section 7.

Volume 1:

• 9 to Love, 5 to Love, Chs. 1-6
• Tengoku ni Ichiban Chikai Shima (A one-shot about a teacher who falls for the older brother of one of his students.)

Volume 2:

• 9 to Love, 5 to Love, Chs. 7-10
• 9 to Love, 5 to Love: Kare wa Katsute, Kare wa Kon, Sarani, Chs. 1-2 (Two side stories set after the main storyline.)
• Sensei no Okiniiri! (A one-shot sequel to Tengoku ni Ichiban Chikai Shima.)