Kunshu no Ai wa Yoru ni Hana Saku

From Fantasyshrine:

St. Cherry Bells, a very prestigious all-boys school, where students are taught to discipline themselves to refrain from sexual practices. Kajiwara Seiji, the president of the Intelligence Department, has a sacred mission—to ensure the purity within the school grounds and to punish those who dare succumb on their urges. But what if the offender turns out to be the man he trusts the most? How would the queen-like Seiji punish his most valuable subject?