Episode 6. And the groups increasingly futile efforts to defeat a Youmu who drenches them in a noxious liquid when it senses danger.
The Yomu is apparently perverted, and can easily be distracted by cute human girls. Mirai and Aki enlist Mitsuki's help. Mitsuki refuses to wear a cutsey outfit in order to distract it, so Mirai agrees to be the one to pose in cosplay in order to do so while she instead kills it with her familiar. The yomu bloats and changes color while Mirai strikes increasingly provocative poses and Mitsuki's familiar gradually gets closer. Only it ate too much earlier and is too tired to attack. Mitsuki winds up getting hit with a particularly pungent fluid. It smells so bad that everyone has to wear gas masks around her. Then her brother shows up, distraught about her text asking for help. He immediately faults upon entering due to the extreme odor. He then quickly tries to regain his composure, complete with a slow-motion hair flip and a Bishie Sparkle, only to immediately fall over and start puking.
The final attempt at defeating it. An idol song and dance number, complete with hilarious Training Montage scene. And at the end…
In episode seven, Hiroomi sends Mitsuki's resume into an idol group audition without her knowing because he'd love to see her dancing in cute outfits in the center of a group of cute girls. Akihito pictures them with glasses as well, and immediately understands. Mitsuki gets back at him by destroying all of his idol CDs and then replacing all the audio on his phone with BL Audiobooks. As they're walking home, Hiroomi tries to stick his earbuds in Aki's ears and force him to listen. There's also Mirai's being the only girl at an all-you-can-eat udon event, and her rushing in at the perfect moment to yell at some baseball players whose ball knocked over one of her bonsai.
Then when Mirai lets her imagination go off over who could be over at Akihito's home…
Mirai is still making spare money by posing for cosplay pictures that Ayaka can sell, and she's still wearing a bunny girl outfit (albeit a tame one) when hanging out with the gang. Akihito tries to get a picture of her, only for Ayaka to take his phone and gesture for him to pay her for the pics. Especially his reaction.
Akihito: Because she doesn't want to walk home with you.
Hiromi: Why not?!
Akihito: Because she hates you.
Hiromi: But why?!
Akihito: Because of the way you act!
Lets face it: every time Akihito and Hiroomi are onscreen together. They either bicker in the most deadpan way ever or they let their imaginations run wild.
The spin-off series, Kyoukai no Kanata Idol Saiban! Here's just the first episode. Akihito is put on trial by chibi Mitsuki, Mirai, and Sakura. The second one is Shizuku. The recent addition, posted by KyoAni's official youtube site, is Hiromi on trial.