Main reason:
The previous name of the tag was a spoiler of its own.
Possible disadvantage:
The new tag may be less intuitive for those who know about the character. I tried to use the shortest possible qualifier to mitigate this.
Also made a new spoiler-free Tohno Shiki (2) wiki entry, as the previous version -see Tohno Shiki (original)- was rife with spoilers (shouldn't it be deleted?).
Updated by スラッシュ