Looking for yaoi manga

I vaguely remember this one so Ill do my best. I remember the black haired teach having sex with, i think, the gym teacher and at first he wasnt interested and i remember the gym(?) teacher had a huge penis and he couldnt fit it all inside the teacher but I think at some point he was able to force it all the way in and the black haired teacher liked it. I remember another teacher coming in who was blonde who wanted to have sex with the black haired teacher but he wasnt interested and the gym(?) teacher was trying to stop his advances. sry if its confusing