I am guessing the author couldn't find a good place to introduce Aki's feeling during the first 5 chapters, but still wanted to have it already in place, either that or it's not going to affect the story for now... still I agree is kinda weird to introduce something like that in an extra ^^;
Thank you for the update! my two favorite mangas (Nettaigyo and Ani no Yone) are currently in dramatic/sad moments so I needed a bit more light