Hello,
I fully respect the named outfits guidelines (howto:named_outfits), which state that variant character tags should generally only be created when the official source gives a proper name to the alternate costume.
However, One Piece is a special case. With over 100 volumes, luffy, robin, Nami’s etc. outfit changes almost completely with nearly every major arc. Relying only on official_alternate_costume plus general clothing tags (such as dress, kimono, etc.) makes it quite difficult for users to efficiently search for specific arc costumes.
Major arcs such as the Water 7 Arc, Whole Cake Island Arc, and Wano Country Arc have well-established official English names that are consistently used in the manga, anime, and official materials. These are not fan-invented names.
As an example, I propose creating a limited number of arc-based variant tags for Nami, for example:
• nami_(water_7)_(one_piece)
• nami_(whole_cake_island)_(one_piece)
• nami_(wano)_(one_piece)
nami_(one_piece) would continue to serve as the umbrella tag,
I believe that using official names, such as the names of each chapter, will reduce the likelihood of unofficial use of tags and confusion.