One day Protagonist Tooru Hiyama discovers injustice of the student election that a student council performed with the whole organization. He with the evidence that may become the great event if announced threatens it to become sexfriend with Iroha of the student council president. To the situation that cannot be refused, she accepts it for one condition to be a secret in the lover.

Thus Iroha, the two-timing life that does sexual intercourse with the sex friend while associating with the lover.