The Irregular at Magic High School THE MOVIE - Yotsuba Succession Arc -(2021)

Looking at Miyuki and Tatsuya now, it might be hard to imagine them as anything other than loving siblings. But it wasn't always this way - Three years ago, Miyuki was always uncomfortable around her older brother. The rest of their family treated him no better than a lowly servant, even though he was the perfect Guardian, watching over Miyuki while she lived a normal middle school life. But what really bothered her was that he never showed any emotions or thoughts of his own. However, when danger comes calling during a fateful trip to Okinawa, their relationship as brother and sister will change forever.