Shakugan no Shana: Reshuffle

While looking for Treasure Tools in Friagne's old hideout, Yuuji and Shana seemingly swap bodies due to the Treasure Tool Reshuffle. They must now go back to Yuuji's house and return to normal without their friends or the other Flame Haze catching on to their situation, all the while feeling a foreboding from Alastor's warnings.

(Source: Shakugan no Shana Wikia)

Reshuffle is a side story exclusively published in the artbook Guren (紅蓮) on February 25, 2005. The first episode of the OVA series Shakugan no Shana S was adapted from this story. Chronologically, it takes place after volume IX and before the prologue and epilogue of volume X and the Shakugan no Shana DS game.