Does anyone know a yaoi manga about the main character''uke'' who never shown us readers h...

Does anyone know a yaoi manga about the main character''uke'' who never shown us readers his eyes until like last chapter. It's about how he always write things on his cellphone secretly about others and one day he found out that two of his classmate were having sex and one of them is being abused. He found that out through a text by a mysterious unknown messenger to his cellphone. It turned out it was the seme''this is not the seme with the MC'' in the abusive relationship with his master''the seme is a worker for the arrogant uke house''.