I presume you're referring to the "男の娘×女の子" tag on the Pixiv post. Unfortunately, with the various redesigns on Pixiv I'm no longer as confident that I know how to tell author-added from reader-added tags.
I presume you're referring to the "男の娘×女の子" tag on the Pixiv post. Unfortunately, with the various redesigns on Pixiv I'm no longer as confident that I know how to tell author-added from reader-added tags.
Hit the tag edit button (the plus or "+" symbol). Author-added tags are locked and can't be removed by users other than the author.
Since 男の娘×女の子 can be removed, it's actually a user-added tag.