Natsume Oharaogi (or similar character)
A prodigy onmyouji and Harutora's childhood friend from the Tsuchimikado clan's main family line. She's best known for showing up during summer break to drag him back into her life—specifically, to make good on a promise he'd made years ago to become her familiar. Heir to the Tsuchimikado name, she's widely believed to be the reincarnation of Yakou Tsuchimikado, which comes with serious weight.
The clan has a long-standing tradition of presenting their heirs as male in formal settings with other onmyouji families, and she follows it without question. That said, her real concern is keeping the family's reputation spotless—something that drives a lot of her decisions, even when it complicates things with Harutora and their actual history together.
Content compiled by AnimeList.moe from publicly available sources.