Mr. Aguro and Mr. Shirai's Gray Love

Cram school teachers, Mr. Aguro and Mr. Shirai are always at odds, and this time, both have their eyes on their student. He rejects both as they know nothing of real love. If either of them wants him, he proposes the date each other temporarily until they discover what it means. Starting out as a simple wager over who gets to date their student, the two begin their complicated relationship. Can these two love virgins find what they're missing?

(Source: MangaPlaza)