The official site lists her as a girl and the show treats her as one, tagging as 1boy is also spoilers and would cause half of the show to get blacklisted unless a significant majority of Lily's fanart depicts her as a boy as such, and the 1other tag is used for ambiguous or non-gendered characters. Unless you have visual confirmation to the contrary, you tag Lily as a girl
The official site lists her as a girl and the show treats her as one, tagging as 1boy is also spoilers and would cause half of the show to get blacklisted unless a significant majority of Lily's fanart depicts her as a boy as such, and the 1other tag is used for ambiguous or non-gendered characters. Unless you have visual confirmation to the contrary, you tag Lily as a girl
Honestly, it feels like that show just pulled this one out of their asses and it was not intended from the start until one of the script writers went "Wouldn´t it be funny if we did that REALLY TRENDY ANIME THING with one of our characters?" and they just went ahead and did it. Not really sure why I spoilerize my comment but whatever.