Yukimura-sensei to Kei-kun
From Yaoi Shake Scans:
It's a story about the student Sunose Kei, who fell in love with the handsome yet cold teacher Yukimura Tsukasa, who looked annoyed everytime his student visited him. Even though Yukimura-sensei can't turn away from Kei, he spends the night with another man. And what's more is that he spends it with his ex-lover?! Now that’s a student-teacher story that you can't miss.