The girl is stunned, blushing, and furious. The protagonist is confused but holding eye contact with her exposed panties (or lack thereof). This "accidental" intimate position (a 69-esque or face-to-crotch orientation) is the payoff. The phrase implies the "fall" is merely the prelude to the "ochi" (the conclusion/punchline).
ロマンチック系（甘め） 夕焼けの窓際、2階から一人の女の子が舞い降りた。ふわりとした笑顔に心を奪われて、僕の平凡な日常が一気に色づいた。これが恋ってやつかな。 joshiochi 2kai kara onnanoko ga futtekita
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