robin_(female)_(seaside_tactician)_(fire_emblem)
Female Robin from Fire Emblem Awakening when dressed in her summer attire from Fire Emblem Heroes' 2017 Ylissean Summer banner.
The Robin unit using this outfit is officially known as Robin: Seaside Tactician
Can typically be identified thanks to the outfit's characteristics: a purple o-ring bikini with a large coat draped over it, a brown belt, large brown boots, a large net containing fish, and a basket containing an octopus.
Likely to include her weapon from the game, a large harpoon with a fish skewered on its points.
Note that it's possible (especially in older artwork) to depict Female Robin in a swimsuit without it being the one described above, in which case this tag should not be used.