The statement comes seemingly out of nowhere.
/Out of nowhere/ because Keiji and Koutaro have been attached at the hip all day, running errands, watching movies, practicing tossing in Koutaro's back yard, making out in bed, and now, making dinner in Koutaro's kitchen.
/Seemingly/ because they've been through this before.
Akaashi doesn't look up from his textbook when he answers; he taps his pencil at the corner of the page he's reading, "Tulip," he says simply.
Bokuto watches him quietly from his bed. They're at the Bokuto family home, studying for finals that are quickly approaching. (Akaashi is studying Statistics; Bokuto is, apparently, studying Akaashi).