Sensei to, Uwakichuu

Sensei to, Uwakichuu summary:

From Chibi Manga: Hana is in extreme shock over the fact that her boyfriend cheated on her. When confiding in the Kudou Sensei from the school infirmary, he rubs her hair… Are you trying to comfort me? When she was trying to leave, he makes an impossible proposition, "Would you like to have an affair with me?"!? Hana who became limp from those words was asked "Are you anemic?" I’m not! He says we should just have an affair to kill time, but Hana doesn’t understand him!!