Triangle Heart:
Miyuki is Kyouya and Nanoha's cousin, though she was raised by their family and considers them siblings. She and Kyouya are exceptionally close and both skilled in the Mikami twin kodachi style. When their childhood friend Fiasse becomes a famous singer and heiress, Miyuki and Kyouya get hired as her bodyguards alongside her official guard Ellis—a partnership that doesn't start smoothly. The three have to learn to work together as they protect Fiasse from a kidnapper during her world concert tour. Miyuki proves herself more than capable, once taking down an entire Special Duties Unit team solo, though she's not someone who enjoys fighting. For her, combat is just a necessary part of protecting the people she cares about.
Mahou Shoujo Lyrical Nanoha:
Here, Miyuki is Nanoha and Kyouya's actual sister. She lives with both of them, plus their parents Momoko and Shirō. Despite being a minor character overall, she and Kyouya remain unusually close and skilled with swords. At one point Nanoha watches Miyuki's solo training, hoping to pick up tips for her own technique with her magical staff Raising Heart. Through the first season, Miyuki stays in the dark about magic entirely—she doesn't learn about Nanoha's powers until the end of A's.
Content compiled by AnimeList.moe from publicly available sources.
