A character cosplaying as one of their own alternate identities, such as a magical girl's civilian identity wearing her magical girl identity's clothes.
It's usually one of the following scenarios:
The outfit doesn't match the wearer's current hairstyle, eye color, scars, personality, etc.
The outfit belongs to a younger version, but the wearer has an older body, or vice versa
Similar to fusion and split theme, but instead of merging, the character looks like they simply changed clothes.
If instead, the hairstyle doesn't match the state of the body, it might be a self-borrowed hairstyle.
The Precure franchise has an unofficial term for this, which is "midform".
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