Jun is an uncle of Eru Chitanda who was reported missing in India. While looking for information on him, Eru got an image of him as a "quiet fighter and kind hero". He didn't finished his high school education due to his expulsion from the Kamiyama High School. Houtarou and his friends determined that Jun was considered as a leader of a student protest movement against the school's administration 45 years ago, in the 1960s. The protests were a reaction to the principal's attempt to cut the school's culture festival from 5 days to 2.
While the protests succeeded in saving the festival duration for a short time, Jun was selected by school's administration as the unfortunate scapegoat and therefore he was expelled in October, after the festival ended. The reason Jun was expelled 5 months after the actual protest in June was to make sure that the students had calmed down.
After telling all of this to his friends Houtarou finally figures out why Jun selected word hyouka for Classics Club's anthology. Hyouka means "ice cream" in English, therefore Jun made the pun of "ice cream" sounding as English phrase "I scream". This he meant as a message for future members of the Classics Club. Upon realizing all of that and frightened by the idea that one could be alive but dead at the same time, and unable to scream, Eru with tears remembered that this was the reason that caused her to cry many years ago.