She first appears in Season 2 episode 11.

She is an older member of the Matoba clan, acting as the current head's secretary and assistant.

The second season of Natsume Yuujinchou. 
As with its prequel, Zoku Natsume Yuujinchou is about Natsume Takashi, a boy who has had the ability to see youkai since he was young, and his bodyguard youkai, Madara, nicknamed Nyanko-sensei. Natsume attempts to return names written in his Book of Friends, which he inherited from his grandmother Reiko, to youkai in his village. Throughout these adventures, he meets some youkai that are friendly, some that want to steal the Book of Friends, and some that want to kill him. Natsume learns about himself and his relationship with youkai along the way. 
(Source: MAL Rewrite)

The third season of Natsume Yuujinchou. 
Takashi Natsume has always been shunned by those around him because of his mysterious ability to see yokai. Eventually, he came into possession of his grandmother Reiko’s “Book of Friends,” and together with his bodyguard Nyanko-sensei he set out to return the names of the yokai contained within it. Since then, he’s found a home with the Fujiwaras and surrounded himself with friends at school. Little does he know he's about to be dragged unwittingly into further trouble... 
(Source: NIS America)

The fourth season of Natsume Yuujinchou. 
 
Still in possession of his grandmother's Book of Friends, Natsume spends his days returning the names of yokai to their rightful owners. He has been learning how to deal with the yokai and humans that surround his life, but the time has come for him to deal with something even more difficult — his own past, and future. 
(Source: NIS America)

The fifth season of Natsume Yuujinchou.

When Reiko was Takashi's age, she bound the names of demons and spirits in her Book of Friends, enslaving them to her capricious whim. Now Takashi is the owner of the book, and the creatures will do anything to get their names back.
 
(Source: VIZ Media)

The seventh season of Natsume Yuujinchou.

Thirteenth episode of Natsume Yuujinchou Shichi released on the 5th Blu-ray volume.

Nanase