隣の席の神崎くんと××してしまった = I have done ×× with Kanzaki in the next seat
となり の せき の かんざき くん と ばつばつ して しまった
est. Rough estimate based on volume count, reprints and magazine — not an official figure
External databases: MADB
How to compare editions, collected volumes and ISBNs / Sources, updates and corrections