Eita begins receiving anonymous love letters in his shoe locker, he tries to to unravel the mystery himself, keeping the letters secret from Chiwa and Masuzu. At first he suspects it might be Chiwa writing those letters.
Masuzu suspects that he is hiding something, but is interrupted by the sudden appearance of her sister Mana, who threatens her with veiled threats involving their father, and steals a kiss from Eita. She refuses to talk about it but is actually bothered by that kiss. Later, Chiwa gets sick, and while he is nursing her he realises that she can`t be the one writing the letters.
Eita receives a third letter, nearly getting caught by Chiwa and Masuzu, this time saying they should meet, and he finds the letters were from a girl he has never seen before, Akishino Himeka, who claims to have been his lover in a past life. She seems to have crafted her chuunibyou fantasies around his, after seeing him fight as "Burning Fighting Fighter". She embraces him, despite his objections, when Chiwa and Masuzu see them.