Tagged fine_art_parody because of the pose (taken directly from the classic Leda and the Swan painting).
Btw is this just a play on "iroha" from the show's title or are there actually girls somehow becoming romantically involved with cranes in the show? Because that would be pretty awesome.
It's actually a Grey Herring, and is seen multiple times throughout the show without any real... interaction. Most often it's seen flying off in the distance or standing on some stairs that Iroha travels up(without even noticing). The only thing I can think it would be for is to reference it being a metaphor for it's literary definition.