Takahashi Katsumi will play Hideto's boss Gonda Kansuke who is a director in the same bank and relishes in being surrounded by young women. Despite being a virgin, he keeps saying things like he's sick of women so as to hide his inferiority complex. When he gets forced to attend Otona Koukou with his subordinate who becomes his classmate, Gonda will have to strive to graduate by losing his virginity. Takahashi who last played Miura's father in the NTV drama SP "Satsujin Hensachi 70" three years ago, praised the latter for being such a nice guy to listen to his boring talk during their breaks while Miura said that he sought a lot of advice from Takahashi as if he was his real father. As for playing a 55-year-old virgin, Takahashi said that this is the first time that he is attempting such a role and wondered if the lines in the drama will get them into trouble with the censors as they are quite provocative and sensational. Nonetheless, he will try his best to play this character and enjoy this unusual experience.
Ryuusei Ryo will play Yamada Pegasasu, the form teacher of Hideto's class and is well-known for his spartan teaching methods and venomous tongue who is not intimidated by having to teach students who are even older than him. Ryuusei commented that he has played many student roles to date so having to play a teacher this time is a new challenge for him. He also called upon the viewers to check out this unique late-night drama with an interesting theme.
As for Matsui Airi, she will play the sexy assistant form teacher Himetani Sakura who boasts of a wealth of sexual experience despite her young age. With respect to this role, Matsui said that she went to consult friends who are just like Sakura and hopes to use that as the basis of her acting in this drama. Having to say quite a lot of provocative and suggestive lines in this drama, Matsui would sometimes wonder if it's OK for her to say such things even though it is for the sake of acting.
Other co-stars include Yamada Maho who plays Hideto's classmate Madara Masumi, a hikkikomori confining herself to her apartment, Jutta Yuki who plays Kawamoto Carlos, a manager of a bento shop, Masana Bokuzo who plays Mochida Mamoru, the assistant form teacher who doesn't have good looks but is married to a very beautiful woman and has 5 lovers and Sugimoto Tetta who plays the school's principal Kakazu Kiichiro and delivers the invitations to enter his school personally to the students.