Twins in Agony by Sakurano Itsuki
Ako and Komachi are twin high schoolers who are famous for being close. They look almost exactly the same, except for the length of their hair. They're also similar in terms of academic performance, but in their latest exams, Ako claimed to be in a "slump" that caused her scores to fall.
Because of this, she has to take remedial English lessons from the assistant homeroom teacher, Oosawa Maki. When asked about the reason for her declining performance, Ako tells her that she was worried about love.