Lovely Complex/Funny

At the start of Episode 14, where she is playing her favorite dating game, being depressed over her latest rejection. The faces she makes in this sequence, combined with the family crying in the hallway, are just hilarious.
Every time Koizumi makes this face.
Haunted House. That is all.
Doubles as a Crowning Moment of Heartwarming: Episode 19, while on a date at a sporting event, Otani and Koizumi have a nice heart-to-heart in which Otani finally makes it clear he does love her. Koizumi's about to break out in tears of happiness... ...and then, there is suddenly massive cheering from the crowd, as Otani and Koizumi realize their entire conversation has been captured on the arena's big screen. Which stays focused on them as they are running away in embarrassment.

Announcer: Good job, buddy!

Otani's reaction to Maity blowing in his ear.
- And Nobu's reaction: "Goosebumps...goosebumps...goosebumps..."
Episode 24: Koizumi's Epic Fail at being a model and Otani's Face Palm reaction to it.
Haruka joking to Kohori that he's Risa's lover and Maity is her man on the side. Actually both times Kohori's lied to.
The gang upon learning that it's almost Risa's birthday: "Smirk...smirk...smirk....smirk....smirk..."
In episode 1 Koizumi sleeping during the entrance ceremony with a big Snot Bubble and suddenly waking up to scream "Damn it! My summon monsters have been annihilated!" only to have the entire room laugh at her in response. And later the teacher asks her "Sleeping while standing? Are you a giraffe?" Koizumi states "I might have been in a past life." And Otani's devil face expression after he sees that Koizumi is in love with Suzuki and he can cause trouble.