Here is Furukawa Airi’s confession, with English subtitles, from AKB 1/149 Renai sousenkyo.
I have to first say that the setting in the confession is kinda weird. The last date gives a little more context to what’s going on here, but basically, Airi has invited you to her special bar / club that she’s apparently a part of. Watching her character here feels a little different from the free and easy character that you witness during the various dates and such.
There isn’t much dialogue here, so there isn’t much in the way of unusual grammar. Similarly, any strange vocabulary is pretty sparse, with the exception of a few choices words:
ごきげんよう（gokigen yo） → This is a really old-fashioned type of greeting, and feels a bit stiff and formal. In my informal experience, I’d expect a rich old woman who is stereotypically refined to speak this way. It feels like a slightly more formal and outdated, “Hello”, so I translated it as “Greetings”.
部外者（ぶがいしゃ, bu-gai-sha） → outsider from a specific group. She she says this during the rejection scene. Since you’re not becoming her important partner, you’re considered an outsider to this little party of hers. Taking apart the individual kanji characters, it’s pretty easy to make out the meaning. 部（ぶ, bu） usually refers to a group, 外（がい, gai）means outside, and 者（しゃ, sha）means person.
The only other thing to note is that the way she talks here is a little… different. Presumably it’s mean to create a more mysterious and mature type of atmosphere. The first indication of her altered speech is evident when she uses ごきげんよう (go-ki-gen-you), instead of something like こんばんは (konbanwa). Lastly is the way she commands you toward the end, during the kiss scene. She says, “もっと近くに来なさい (motto chikaku ni kinasai)”. Saying 来なさい（kinasai) is the much more formal command form of 来て(kite), which means, “to come”, and contributes to the more formal and mature type of ambiance.
Here is the Japanese dialogue:
As usual, here are some alternate photos of Airin for your viewing pleasure (^^
Sometimes editor. Sometimes translator. Mostly a proofreader. I like Japan and things.