I'll Answer Your Mystery.

My role is to take care of her—and to deduce "her deduction." "I shall prove the truth that you have found." An assistant to the high school counseling teacher, Rinne Akegami is an introvert who only understands what is true. As if from a revelation from God, she can point out the culprit of any crime there. What complicated matters, however, is that not even she herself understands how she does this! This is where Touya Iroha comes in—he deduces "her deductions" in order to reveal the truth, once and for all!