kannagi_itsuki from Sorakake is, as is never actually hidden from the audience, also known as Shimoyama Mutsumi when she's going undercover at Akiha's school. She takes on a very different look (glasses, long green hair) when in this disguise.
Currently, she is tagged only as kannagi_itsuki regardless of which appearance she's taken on. How do people feel about using both character tags for her when she's in Mutsumi guise, much like exkeine/kamishirasawa_keine? Implicating Kannagi to Mutsumi, of course, but not the reverse.
Normally, I object to tags that only serve to spoil, however I don't think this case qualifies as such. Also, seeing it tagged just as Itsuki already kinda gives it away, not that there's anything to hide... Given that, I think it's worthwhile to give people the ability to search for one or the other of her appearances, either by searching just Mutsumi, or Itsuki -Mutsumi.
Updated by Log