You walked into the living room, where you spot Blaze and Sapphire sitting on the couch. When you called out to them, you became confused upon seeing Blaze with a happy expression.

Blaze: "Y/N!! Don't we look beautiful?" You were confused but smiled and waved at her but then your suspicions were risen when you saw Sapphire's express.

Sapphire: "H-Hmph.."

Blaze: Ah, don't be like that Onee-Chan, this was an awesome idea! Their even blushing!"

Sapphire: "Stop encouraging their perverted mind, Saph!"

At that moment you realized... The way they are actually and that Sapphire called Blaze, "Saph"...

They had swapped bodies.