Unaired episode 13 of Aoharu x Kikanjuu bundled with BD/DVD volume 6.

Mature grade school student Arisu Tachibana is an aspiring idol who receives an invitation from her company president to participate in the Third Entertainment Section—a new idol project. Arisu and eight other young girls soon meet their producer before beginning idol-related activities. To the girls' surprise, their producer appears to be a childlike adult and nothing like what they had imagined. The producer, who is taking on the position for the first time, also had no idea that he would be meeting a group of short, young idols. The awkward situation leaves Arisu disappointed, and she wishes for a producer change. However, the producer, with his genuine love for idols and his desire to see them shine, will not let this opportunity pass and expresses that he is serious about working with the girls. Thankfully, the young idols accept the producer after seeing his unwavering passion for idols, serving as the start of their journey to the stage of dreams.

After Niche carries the wounded and stunned Lag back to the Bee Hive, the Letter Bee finally begins to piece the puzzle together. Now he knows what's happened to Gauche, why the Marauders are so focused on stealing mail and the actual intent of the group controlling both, Reverse. However, when he's forbidden to reveal the truth, Lag is soon forced out of the artificial sunlight and back into the world of perpetual night. And soon Reverse's plot to take down the Letter Bees and overthrow the Amberground government begins to accelerate. If things weren't already bad enough, the giant insect creatures called gaichuu are apparently evolving into something new; there may be traitors working within the Hive; and Niche's sister, who's definitely not human friendly, shows up to turn family drama into a full-scale siege! It all spells serious trouble for the Letter Bees, but if anyone can weather the storms and gloom of night, Lag and his team are the ones who'll deliver. (Source: FUNimation)

Kyuu is your average boy with a knack for logic and reasoning. Desiring to become a detective, he finds out about the existence of the Dan Detective School (DDS); a famed school where students are allowed to bear arms. Together with Megu, a girl with photographic memory, the martial arts master Kinta, the genius programmer Kazuma and the mysterious Ryuu, Kyuu tackles many well planned out crimes, always seeking the truth.